Question

If 4x - 3y = 12 and xy = 5 , then find the value of$\frac{16x^2+9y^2}{8}$

• A. 33
• B. 15
• C. 18
• D. 44

Answer 1

Answer:

A. 33

4x - 3y = 12

$(4x-3y)^2=12^2$

$16x^2+9y^2-24xy=144$

$16x^2+9y^2-24\times5 = 144$

$16x^2+9y^2=144+120=264$

$\frac{16x^2+9y^2}{8}=264/8$

$=33$