Question

4 Ejercicios:

a) 2x2 + 5x = –6

b) 3x2 – 7x = –12

c) 4x2 – x = 20

d) 5x2 = 11x – 30

Answer 1

A). 2x2 + 5x = –6

4 × 5x = - 6

4 + 5x = - 6 - 4

5x = - 6 - 4

- (6 + 5)

= - 10

5x = - 10

5x ÷ 5 = - 10 ÷ 5

= x = - 2

B). 3x2 – 7x = –12

6 - 7x = - 12

- 7x = - 12 - 6

- (12 + 6)

- 7x = - 18

x = 18/7

C). 4x2 – x = 20

8 - x = 20

- x = 20 - 8

- x = 12

x = - 12

D) 5x2 = 11x – 30

10 = 11x - 30

- 11x + 10 = - 30

- 11x = - 30 - 10

- 11x = - 40

-11x ÷ (- 11) = - 40 ÷ (- 11)

x = 40/11