Question

if a-b =7 a2 + b 2 = 85 find a2 - b2​

Answer 1

Answer:

a-b=7

a^2+b^2=85

=> (a-b)^2+2ab=85

=> 7^2+2ab=85

=> 2ab=85-49

=> 2ab=36

again a^2+b^2=85

=> (a+b)^2-2ab=85

=> (a+b)^2-36=85

=> (a+b)^2=85+36

=> (a+b)^2=121

=> (a+b)=√121=11

a^2-b^2

=(a+b)(a-b)

=11×7

=77