Question

Find the value of x + y, given that 9x^2 - 9y^2 = 72 and x - y = 1.5​

Answer 1

`5(1)/(3)`

Explanation:

`\boxed{a^(2) -b^(2) = (a +b)(a -b)}`

9x² -9y²= 72

Factorise:

9(x² -y²)= 72

Divide both sides by 9:

x² -y²= 8

(x +y)(x -y)= 8

Given that x -y= 1.5,

(x +y)(1.5)= 8

Divide both sides by 1.5:

x +y=
`5(1)/(3)`