Question

Solve for x: 2x^2 - 4x - 14 = 0
I have everything up to 2(x-2)^2=6, but I do not know how to continue.

Answer 1

2(x^2 - 2x - 7) = 0
Δ = 4 - ( -28) = 32
x = (-4 ± 4 √2)/ 4 = -1 ± √2

Answer 2

Oops,
x = (-4 ± 4 √2)/ 2 = -2 ± 2√2

Answer 3

I dont understand Δ... I am only in Algebra II

Answer 4

2x^2 - 4x - 14 = 0

divide everything by 2 in order to get x^2 by itself without the coefficient

x^2 - 2x - 7 = 0

and then use the quadratic formula

(-b+-sqrt(b^2 - 4ac))/2a

(2 +or- sqrt(4 - 4*1*-7))/2

(2 + sqrt(32)) / 2 and (2 - sqrt(32))/2

2 + 4sqrt(2) / 2 and 2 - 4sqrt(2) / 2

1 + 2sqrt(2) and 1 - 2sqrt(2)

Answer 5

That's quadratic formula in algebra II

Answer 6

Only quadratic formula can solve any cases!

Answer 7

Thank You Both!

Answer 8

S's result is perfect, not typo as mine!