Question

(2x+78)(5x+15) what is x

Answer 1

10x^2+420x+1170

Explanation:

(2x+78) (5x+15)

2x (5x+15)+78(5x+15)

10x^2+30x+78(5x+15)

10x^2+30x+390x+1170

10x^2+420x+1170

Answer 2

2x * 5x = 10 ²
2x * 15 = 30x
78 * 5x = 390x
78 * 15 = 1170

10x ² + 30x + 390x + 1170
= 10x ² + 420x + 1170