Question

If 3x - y = 5 and 2x + y = 15 , evaluate x ^ 2 + 2y​

Answer 1

x² + 2y = 30

Explanation:

given

3x - y = 5 → (1)

2x + y = 15 → (2)

Solve the equations simultaneously for x and y

adding the 2 equations term by term will eliminate y

(2x + 3x) + (y - y) = 15 + 5

5x + 0 = 20

5x = 20 ( divide both sides by 5 )

x = 4

substitute x = 4 into either of the 2 equations and solve for y

substituting into (2)

2(4) + y = 15

8 + y = 15 ( subtract 8 from both sides )

y = 7

solution is x = 4 , y = 7

Then

x² + 2y = 4² + 2(7) = 16 + 14 = 30