Question

how to do sum number 14

Answer 1

3x + 4y = 16 & xy = 4
9x² + 16y² = (3x)² + (4y)² = (3x+4y)² - 2*3x*4y = 16² - 24*4 = 256 - 96 = 160

Answer 2

Given Equation is 3x + 4y = 16.

On Squaring both sides, we get

(3x + 4y)^2 = (16)^2

9x^2 + 16y^2 + 2 * 3x * 4y = 256

9x^2 + 16y^2 + 24(xy) = 256

9x^2 + 16y^2 + 24 * 4 = 256

9x^2 + 16y^2 + 96 = 256

9x^2 + 16y^2 = 256 - 96

9x^2 + 16y^2 = 160.


Hope this helps!