If 5x + 3y=4 and 5x-3y= 2, what is the value of (25x\(^2\) -9y\(^2\))?
A
20
B
16
C
2
D
8
Verified Correct Answer: D.
Step-by-Step Mathematical Solution
5x + 3y=4
5x-3y= 2
Using elimination method
5x + 3y=4 → 5x + 3y=4
-[5x-3y= 2] → -5x +3y= -2
6y = 2
y → 1/3 and x = 3/5
solving (25x\(^2\) -9y\(^2\))
25 * [3/5]\(^2\) -9 * [1/3]\(^2\)
25 * \(\frac{9}{25}\) - 9 \(\frac{1}{9}\)
9 - 1 = 8
Source: WAEC / JAMB / NECO Classroom Archive (Record #64804)