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Mathematics
UTME / JAMB 1999
Indices, Logarithms & Surds
Solution
Find the value of X if \(\frac{\sqrt{2}}{x+\sqrt{2}}=\frac{1}{x-\sqrt{2}}\)
A
3√2+4
B
3√2-4
C
3-2√2
D
4+2√2
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
Start your solution by cross-multiplying,
\(\frac{\sqrt{2}}{x+\sqrt{2}}=\frac{1}{x-\sqrt{2}}\)
[x - \(\sqrt{2}\)]\(\sqrt{2}\) = x + \(\sqrt{2}\)
where \(\sqrt{2}\) \times\(\sqrt{2}\) = 2
x\(\sqrt{2} - \sqrt{2} x \sqrt{2}\) = x + \(\sqrt{2}\)
then collect like terms
x\(\sqrt{2}\) - x = \(\sqrt{2}\) + 2
and factorize accordingly to get the unknown.
x(\(\sqrt{2}\) - 1) = \(\sqrt{2}\) + 2
x = \(\frac{\sqrt{2}) + 2}{\sqrt{2} - 1}\)
rationalize
x = \(\frac{\sqrt{2} + 2}{\sqrt{2} - 1}\) * \(\frac{\sqrt{2} + 1}{\sqrt{2} + 1}\)
x = \(\frac{\sqrt{4} + \sqrt{2} + 2\sqrt{2} + 2}{\sqrt{4} + \sqrt{2} - \sqrt{2} - 1}\)
x = \(\frac{2 + 3\sqrt{2} + 2}{2 - 1}\)
x = \(\frac{3\sqrt{2} + 4}{1}\)
x = 3\(\sqrt{2}\) + 4
Source: Myschool Past Questions Archive (Record #10)
Mathematics
UTME / JAMB 1999
Binary Operations, Matrices & Determinants
Solution
Find the matrix T if ST = I where S = \(\begin{pmatrix} -1 & 1 \\ 1 & -2 \end{pmatrix}\)
A
\(\begin{pmatrix} -2 & -1 \\ -1 & -1 \end{pmatrix}\)
B
\(\begin{pmatrix} -2 & -1 \\ -1 & 1 \end{pmatrix}\)
C
\(\begin{pmatrix} -1 & -1 \\ 0 & -1 \end{pmatrix}\)
D
\(\begin{pmatrix} -1 & 1 \\ 0 & 1 \end{pmatrix}\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
S = \(\begin{pmatrix} -1 & 1 \\ 1 & -2 \end{pmatrix}\)
and ST = I (Identity matrix).
This means T is the inverse of S
Find the determinant of S
\( \det(S)\) = (-1)(-2) - (1)(1) = 2 - 1 = 1
T = \(\frac{1}{\det(S)} \begin{pmatrix} -2 & -1 \\ -1 & -1 \end{pmatrix}\)
Since det = 1,
T = \(\begin{pmatrix} -2 & -1 \\ -1 & -1 \end{pmatrix}\)
T = \(\begin{pmatrix} -2 & -1 \\ -1 & -1 \end{pmatrix}\)
Source: Myschool Past Questions Archive (Record #11)
Mathematics
UTME / JAMB 1999
Plane Geometry, Polygons & Circle Theorems
Solution
If \(\frac{({a^2b^{-3}c})^{3/4}}{a^{-1}b^4c^5}\) = \(a^p b^q c^r\); what is the value of p+2q?
A
(5/2)
B
-(5/4)
C
-(25/4)
D
-10
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
= \(\frac{(a^2)^{3/4}\times(b^{-3})^{3/4}\times c^{3/4}}{a^{-1} b^4 c^5}\) \(= a^p\times b^q\times c^r\)
= \(\frac{a^{3/2}\times b^{-9/4} \times c^{3/4}}{a^{-1}b^4c^5}\) = \(a^p b^q c^r\) = \(a^{{3/4}+1} b^{{-9/4}-4} c^{{3/5}-5}\) = \(a^pb^q c^r\)
= \(a^{5/2} b^{-25/4} c^{-17/4}\) = \(a^pb^qc^r\)
therefore, p=5/2, q=-25/4 and r = -17/4
2a + q = \(\frac{5}{2} - 2\times\frac{-25}{4}\)
= -20/2 = -10
Source: Myschool Past Questions Archive (Record #12)
Mathematics
UTME / JAMB 1999
Fractions, Decimals, Percentages & Approximations
Solution
A trader bought 100 oranges at 5 for N1.20, 20 oranges got spoilt and the remaining were sold at 4 for N1.50. Find the percentage gain or loss.
A
30% gain
B
25% gain
C
30% loss
D
25% loss
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Cost price (cp) = (100/5) x N1.20 =N24.00
Selling price (sp) = 100-20 = 80
(80/4) x N1.50 = N30.00
Gain = SP-CP = N30.00-N24.00 = N6.00
Gain% = (gain/CP) x 100 = 25%
Source: Myschool Past Questions Archive (Record #13)
Mathematics
UTME / JAMB 1999
Number Bases & Modular Arithmetic
Solution
What is the answer when 2434\(_6\) is divided by 42\(_6\)?
A
236
B
356
C
526
D
556
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Hint: Two methods can be used;
1. Direct division (if you know division in number bases)
2. Convert both sides to base 10, divide and convert your answer back to base 6. Your answer should be 356
2434\(_6\) to base 10
2 \(\times\) 6\(^3\) + 4 \(\times\) 6\(^2\) + 3 \(\times\) 6\(^1\) + 4 \(\times\) 6\(^0\)
2 \(\times\) 216 + 4 \(\times\) 36 + 3 \(\times\) 6 + 4 \(\times\) 1
432 + 144 + 18 + 4 = 598
And: 42\(_6\) to base 10
4 \(\times\) 6\(^1\) + 2 \(\times\) 6\(^0\)
4 \(\times\) 6 + 2 \(\times\) 1
24 + 2 = 26
Then divide 598 by 26
= 23
Then convert 23\(_{10}\) to base 6
6
23
6
3 r 5
6
0 r 3
23\(_{10}\) = 35\(_6\)
Source: Myschool Past Questions Archive (Record #14)
Mathematics
UTME / JAMB 1999
Indices, Logarithms & Surds
Solution
If 2\(_9\) x (Y3)\(_9\) = 3\(_5\) x (Y3)\(_5\), find the value of Y.
A
4
B
3
C
2
D
1
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
(2 x 9 \(^0\) ) (Y x 9 \(^1\)+ 3 x 9\(^0\)) = (3 x 5 \(^0\))(Y x 5\(^1\) + 3 x 5\(^0\)).
(2 * 1)(Y *9 + 3) = (3 * 1)(Y * 5 + 3)
18y + 6 = 15y + 9
18y - 15y = 9 - 6
3y = 3
y = 1
Source: Myschool Past Questions Archive (Record #15)
Mathematics
UTME / JAMB 1999
Indices, Logarithms & Surds
Solution
Simplify \(\sqrt{\frac{(0.0023 \times 750)}{(0.00345 \times 1.25)}}\)
A
15
B
20
C
40
D
75
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Multiply appropriately to remove decimals on both numerator and denominators.
Such that you have \(\sqrt{\frac{(23000 \times 750)}{(345 \times 125)}}\)
Dividing, => \(\sqrt{400} = 20\).
Source: Myschool Past Questions Archive (Record #16)
Mathematics
UTME / JAMB 1999
Binary Operations, Matrices & Determinants
Solution
If \(m*n = (\frac{m}{n} - \frac{n}{m}\)) for m, n belong to R, evaluate -3*4
A
\(\frac{-25}{12}\)
B
\(\frac{-7}{12}\)
C
\(\frac{7}{12}\)
D
\(\frac{25}{12}\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(m*n = \frac{m}{n}-\frac{n}{m}
= \frac{-3}{4} - \frac{4}{-3}
= \frac{-3}{4} + \frac{4}{3}
= \frac{(-9+16)}{12}
= \frac{7}{12}\)
Source: Myschool Past Questions Archive (Record #17)
Mathematics
UTME / JAMB 1999
Plane Geometry, Polygons & Circle Theorems
Solution
The sum of two numbers is twice their difference. If the difference of the numbers is P, find the larger of the two numbers
A
p/2
B
3p/2
C
5p/2
D
3p
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Let the numbers be x and y
x+y = 2p.....(i)
x-y = p......(ii)
2x = 3p
x = 3p/2
Source: Myschool Past Questions Archive (Record #18)
Mathematics
UTME / JAMB 1999
Binary Operations, Matrices & Determinants
Solution
A binary operation * is defined by a*b = ab+a+b for any real number a and b. if the identity element is zero, find the inverse of 2 under this operation.
A
2/3
B
1/2
C
-1/2
D
-2/3
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(a*a^{-1} = aa^{-1} + a + a^{-1} = e\)
if e = 0
\(2.2^{-1} + 2 + 2^{-1} = 0\)
collecting like terms, we have:
\(3.2^{-1} + 2 = 0\)
= \(2^{-1}\) = -\(\frac{2}{3}\)
Source: Myschool Past Questions Archive (Record #19)
Mathematics
UTME / JAMB 1999
Algebraic Expressions, Polynomials & Factorisation
Solution
Factorize completely \(x^{2} + 2xy + y^{2} + 3x + 3y - 18\).
A
(x+y+6)(x+y-3)
B
(x-y-6)(x-y+3)
C
(x-y+6)(x-y-3)
D
(x+y-6)(x+y+3)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
Expand the options and collect like terms to check which gives the presented expression.
Expansion of Options A:
(x+y+6)(x+y-3) → \(x^2+xy-3x + xy+y^2-3y +6x+6y-18\)
Collect like terms: \(x^2 + xy + xy + y^2 +6x - 3x +6y - 3y - 18\)
= \(x^2 + 2xy + y^2 + 3x + 3y - 18\)
Source: Myschool Past Questions Archive (Record #20)
Mathematics
UTME / JAMB 1999
Plane Geometry, Polygons & Circle Theorems
Solution
Three consecutive positive integers k, l and m are such that l\(^2\) = 3(k+m). Find the value of m.
A
4
B
5
C
6
D
7
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
l\(^2\) = 3 (k + m)
Since they are consecutive positive numbers, we have
l = k+1, m = k+2.
\(\to\) (k+1)\(^2\) = 3(k + k + 2)
k\(^2\) + 2k + 1 = 3(2k + 2)
k\(^2\) + 2k + 1 = 6k + 6
k\(^2\) + 2k - 6k + 1 - 6 = 0
k\(^2\) - 4k - 5 = 0
k\(^2\) - 5k + k - 5 = 0
k(k - 5) + 1(k - 5) = 0
k = -1 or 5
Since k, l and m are positive, then k = 5.
m = k + 2 = 5 + 2
= 7.
Source: Myschool Past Questions Archive (Record #22)
Mathematics
UTME / JAMB 1999
Algebraic Expressions, Polynomials & Factorisation
Solution
Express \(\frac{1}{x^{3}-1}\) in partial fractions
A
\(\frac{1}{3}(\frac{1}{x - 1} - \frac{(x + 2)}{x^{2} + x + 1})\)
B
\(\frac{1}{3}(\frac{1}{x - 1} - \frac{x - 2}{x^{2} + x + 1})\)
C
\(\frac{1}{3}(\frac{1}{x - 1} - \frac{(x - 2)}{x^{2} + x + 1})\)
D
\(\frac{1}{3}(\frac{1}{x - 1} - \frac{(x - 1)}{x^{2} - x - 1})\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\(\frac{1}{x^{3} - 1}\)
\(x^{3} - 1 = (x - 1)(x^{2} + x + 1)\)
\(\frac{1}{x^{3} - 1} = \frac{A}{x - 1} + \frac{Bx + C}{x^{2} + x + 1}\)
\(\frac{1}{x^{3} - 1} = \frac{A(x^{2} + x + 1) + (Bx + C)(x - 1)}{x^{3} - 1}\)
Comparing the two sides of the equation,
\(A + B = 0 ... (1)\)
\(A - B + C = 0 ... (2)\)
\(A - C = 1 ... (3)\)
From (3), \(C = A - 1\), putting that in (2),
\(A - B = -C \implies A - B = 1 - A\)
\(2A - B = 1 ... (4)\)
(1) + (4): \(3A = 1 \implies A = \frac{1}{3}\)
\(A = -B \implies B = -\frac{1}{3}\)
\(C = A - 1 \implies C = \frac{1}{3} - 1 = -\frac{2}{3}\)
\(\therefore \frac{1}{x^{3} - 1} = \frac{1}{3(x - 1)} - \frac{x - 2}{3(x^{2} + x + 1)}\)
= \(\frac{1}{3}(\frac{1}{x - 1} - \frac{(x + 2)}{x^{2} + x + 1})\)
Source: Myschool Past Questions Archive (Record #23)
Mathematics
UTME / JAMB 1999
Sequences & Series (AP & GP)
Solution
The first term of a geometric progression is twice its common ratio. Find the sum of the first two terms of the G.P if its sum to infinity is 8.
A
8/5
B
8/3
C
72/25
D
56/9
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
Let the common ratio be r so that the first term is 2r.
Sum, s = \(\frac{a}{1-r}\)
ie. 8 = \(\frac{2r}{1-r}\)
8(1-r) = 2r,
8 - 8r = 2r
8 = 2r + 8r
8 = 10r
r = \(\frac{4}{5}\).
where common ratio (r) = \(\frac{second term(n_2)}{first term(a)}\),
r = \(\frac{n_2}{2r}\)
r = \(\frac{4}{5}\) and a = 2r or \(\frac{8}{5}\)
\(\frac{4}{5}\) * \(\frac{8}{5}\) = n\(_2\)
\(\frac{32}{25}\) = n\(_2\)
The sum of the first two terms = a + n\(_2\)
= \(\frac{8}{5}\) + \(\frac{32}{25}\)
= \(\frac{40 + 32}{25}\)
= \(\frac{72}{25}\)
Source: Myschool Past Questions Archive (Record #24)
Mathematics
UTME / JAMB 1999
Linear, Simultaneous & Quadratic Equations
Solution
Divide 4x\(^3\) - 3x + 1 by 2x - 1
A
2x2-x+1
B
2x2-x-1
C
2x2+x+1
D
2x2+x-1
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
2x\(^2\)
+ x
- 1
2x - 1
4x\(^3\)
+ 0x\(^2\)
- 3x
+ 1
-
4x\(^3\)
- 2x\(^2\)
2x - 1
+ 2x\(^2\)
- 3x
+ 1
-
-x
+ 1
2x - 1
- 2x
+1
-
- 2x
+ 1
0
0
Thus, Divide 4x\(^3\) - 3x + 1 by 2x - 1 = 2x\(^2\) + x - 1
Source: Myschool Past Questions Archive (Record #25)