Question

8. If 2x + 3y = 8 and xy = 2, find the value of 4x2 + 9y?
​

Answer 1

Answer:

40

Step-by-step explanation:

(2x + 3y) = 8 ----(i)

xy = 2

Squaring equation (i) ;

(2x + 3y)² = 8²

=> 4x² + 9y² + 2.(2x).(3y) = 64

=> 4x² + 9y² + 12xy = 64

=> 4x² + 9y² = 64 - 12xy

=> 4x² + 9y² = 64 - 12 x 2

=> 4x² + 9y² = 64 -24

=> 4x² + 9y² = 40