How do you solve this problem with the Quadratic Formula?
x^2 - 3x - 21 = 0
Anyone that can help is highly appreciated! Thanks!
2007-09-01 18:26:39 · 6 answers · asked by Kelly 3 in Science & Mathematics ➔ Mathematics
for this you have to know the quadratic formula:
.........-b±√(b²-4ac)
x = ----------------------
....................2a
a = 1
b = -3
c = -21
x = [3 ± √(93)] /2
2007-09-01 19:11:43 · answer #1 · answered by 037 G 6 · 0⤊ 0⤋
its pretty simple.
the quadratic formula is -b+- the square root of b^2-2ac all divided by 2.
In this problem a=1 because there is nothing in front of the x
b=-3 and c=-21
just fill in the blanks and solve
2007-09-01 18:43:19 · answer #2 · answered by Anonymous · 0⤊ 1⤋
one way is to use the quadratic formula
3 plus or minus the square root of 9 minus 4(-21)(1)
divided by 2(1)=
3+or- square root of 93 all over(divide by) 2
2007-09-01 18:43:09 · answer #3 · answered by SK07KS 2 · 0⤊ 1⤋
quadratic formula:
-b(+/-)("the square root of" b^2-4ac)/(2a)
The basic equation ax^2 + bx +c
Your equation: x^2 - 3x - 21
Just plug in the numbers now.
2007-09-01 18:41:57 · answer #4 · answered by matthew t 3 · 0⤊ 1⤋
for a general formula
ax^2 + bx + c = 0
use the formula
x = [-b +/- sqrt (b^2 - 4ac)]/ 2a
in this particular case [ 3 +/- sqrt(9 + 4 x 27)]/2
=> [3 +/- 3sqrt13]/2
2007-09-01 18:39:30 · answer #5 · answered by Aslan 6 · 1⤊ 1⤋
put d square =b square - 4 ac
2007-09-01 18:34:54 · answer #6 · answered by Anonymous · 0⤊ 1⤋