Question

if 2x+3y=8 and xy=2, find the value of 4x²+9y²

Answer 1

I hope it helps you

Answer 2

Using the identity (a + b)² = a² + b² + 2ab

(2x + 3y)² = (8)² {squaring both the sides}

=> (2x)² + (3y)² + 2 × 2x × 3y = 64
=> 4x² + 9y² + 12xy = 64

Given xy= 2
12xy = 12 × 2 = 24

so 4x² + 9y² + 12xy = 64
=> 4x² + 9y² + 24 = 64
4x² + 9y² = 64 - 24
4x² + 9y² = 40



Hope it helps dear friend ☺️✌️