Question

If the value of X - 5 = y and x² - y² = 15 then how much is x+ y =?

Answer 1

x + y = 4 - 1 = 3.

Explanation:

First, in order to solve for the sum of x and y, we should substitute (x - 5 = y) into our given equation of x² - y² = 15.

Given:

• x - 5 = y
• x² - y² = 15

Substitute:

x² - (x - 5)² = 15.

Use the FOIL Method:

x² - x² + 10x - 25 = 15.

Simplify:

10x - 25 = 15

10x = 40

x = 4.

Solve for y by substitution:

4 - 5 = -1 (y)

x = 4.

y = -1.

Therefore,

x + y = 4 - 1 = 3.