Question

simplify (9x+5y)²-(9x-5y)².

Answer 1

Step-by-step explanation:

by property (a+b)² = a² + 2ab + b²

and (a-b)²= a² -2×a×b +b²

=(9x+5y)² - (9x-5y)²

=[(9x)²+ 2×9x×5y + (5y)²] - [(9x)² -2×9x×5y +(5y)²]

=[ 81x² +90xy + 25y²] -[ 81x² - 90xy+ 25y²]

=81x² + 90xy + 25y² - 81x² +90xy - 25y²

=81x²-81x² + 90xy+90xy +25y²-25y²

=0 + 180xy + 0

=180xy !

hope it helps ?