If x^2 - 2x - 4 = 0, then x = ?

0 ⤊

If x^2 - 2x - 4 = 0, then x = ?

I got

1 +or- 5^1/2

2006-09-01 10:49:40 · 3 answers · asked by chris 2 in Science & Mathematics ➔ Mathematics

3 answers

x^2 - 2x - 4 = 0

x = (-b ± sqrt(b^2 - 4ac))/2a

x = (-(-2) ± sqrt((-2)^2 - 4(1)(-4)))/(2(1))
x = (2 ± sqrt(4 + 16))/2
x = (2 ± sqrt(20))/2
x = (2 ± sqrt(4 * 5))/2
x = (2 ± 2sqrt(5))/2
x = 1 ± sqrt(5)

You are 100% correct.

2006-09-01 15:55:43 · answer #1 · answered by Sherman81 6 · 0⤊ 0⤋

(1 +/- 5^1/2) / 2

2006-09-01 17:53:05 · answer #2 · answered by Embliri Trex 3 · 0⤊ 0⤋

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

2 +- sqrt(4 - 4(1)(-4))
________________
2

2 +- sqrt(20)
__________
2
sqrt(20) = 4.472
2 + 4.472 / 2 = 3.236
2 - 4.472 / 2 = 1.236

Answers (3.236, 1.236)

2006-09-01 17:57:34 · answer #3 · answered by RobRetz 2 · 0⤊ 0⤋