Question

Solve 2x^2+9x-7=0
Give your solutions correct to 3 significant figures.

Answer 1

X = -1 or X = -3.5

Explanation:

2x^2 + 9x + 7 = 0

ac = 14

b = 9

find a two numbers which when you multiply you get 14 and add you get 9.

so it will 2 and 7. (they replace b which is 9x)

therefore: 2x^2 + 2x + 7x + 7 = 0

find common factors using each 2 from the four.

2x( x + 1) + 7 (x+1) = 0

so it will be (2x + 7) (x+1) = 0

find x,

i) 2x +7 = 0

x= -3.5

ii) x + 1 = 0

x = -1