62.1k views
19 votes
Given that 2x^2 - 2y^2 = 40 and x-y=5, find the value of (x+y)

1 Answer

13 votes

Answer:

x+y=4

Explanation:

hello :

note : by identity you have x²-y² = (x-y)(x+y)

in this exercice : 2x²-2y² = 2(x²-y²) = 2 (x-y)(x+y)

means : 2 (x-y)(x+y) = 40

but x-y = 5

so : 2(5)(x+y) =40

x+y=40/10

x+y=4

User AzizStark
by
7.1k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.