Please help me with this quadratic equation!?

0 ⤊

If the expression x^2 - kx - 12 is equal to zero when x=4, what is the value of k?

2007-05-05 07:14:19 · 3 answers · asked by ghafoors2005 1 in Science & Mathematics ➔ Mathematics

x² - kx - 12 = 0
(4)² - 4k - 12 = 0
16 - 12 = 4k
4 = 4k
k = 4/4
k = 1
<>

2007-05-05 09:09:18 · answer #1 · answered by aeiou 7 · 0⤊ 0⤋

16 - 4k - 12 = 0
4 - 4k = 0
k = 1

2007-05-05 07:22:18 · answer #2 · answered by Como 7 · 0⤊ 0⤋

sub in x=4

16-4k-12=0

4k =4

k=1

2007-05-05 07:21:04 · answer #3 · answered by SS4 7 · 0⤊ 0⤋