Question

if 9 x square + 49 y square is equal to 85 and xy is equal to 2 find 3 x + 7 y​

Answer 1

Answer:

step by step explanation

Hi ,

3x -7y = 10 ---- ( 1 ) ,we get ,

Do the Square of equation ( 1 ) , we get ,

( 3x - 7y ) square = 10 square

( 3x )square + ( 7y )square - 2 × 3x × 7y = 100

9xsquare+49ysquare-42×(- 1 ) = 100

9x square + 49y square + 42 = 100

9x square + 49y square = 100 - 42

= 58

I hope this is help for you