Question

3x-4y=10, xy=-1 then 9x²+16y²=?​

Answer 1

Answer:

is 76.

Step are as follow :

$3x - 4y = 10 \\ squaring \: both \: sides \\ {(3x - 4y)}^{2} = {10}^{2} \\ {9x}^{2} + {16y}^{2} - 24xy = 100 \\ {9x}^{2} + {16y}^{2} + 24 = 100 \\ {9x}^{2} + {16y}^{2} = 100 - 24 = 76$

Answer 2

Answer:

this is correct.................................