Answer:
That would be :
4x – 10 = x2 – 5x + 10 ( y = 4x - 10 is substitute for y)
PROOF: y + 5x = x² + 10
(4x - 10) + 5x = x² + 10
4x - 10 = x² -5x + 10
0 = x2 – 9x + 20 (liked terms are grouped and simplified)
PROOF: 4x - 10 = x² -5x + 10
4x = x² -5x + 10 + 10
0 = x² -5x -4x + 20
0 = x² - 9x + 20
Solving:
x² - 9x + 20 = 0
x² - 5x - 4x + 20 = 0
(x - 5) (x - 4) = 0
⇒ x = 4 (as question says) OR x = 5
Explanation:
hope this helps