Im in honors geometry and im stumped on this one question.
x(x) - 6x = 1/2x + 42
x(x) means xsquared 1/2 half x
2006-10-01 01:39:21 · 8 answers · asked by nehemiah3131 2 in Science & Mathematics ➔ Mathematics
lets keep fractions out of this problem and multiply everything by 2. You get:
2x(x) - 12x= x + 84
Let's move everything to one side of the equation:
2x(x) - 13x - 84 = 0
Factor:
(2x - 21 ) ( x + 4) = 0
Set both factors equal to zero and find x
2x - 21 = 0
+21 +21
2x = 21
x = 10.5
x - 4 = 0
+4 +4
x = 4
2006-10-01 04:47:25 · answer #1 · answered by Jose G D 2 · 0⤊ 0⤋
ok I think you want to solve for x, so:
x^2 - 6x = 1/2x + 42
rewrite the equation so it equals zero:
x^2 - 6x -1/2x -42 = 0
combine like terms:
x^2 - 6 1/2x -42 = 0
since there are no two numbers which when added, equal -6 1/2 but when multiplied equal -42, you have some extra work to do:
x^2 - 13/2x - 42 = 0
Use the quadratic formula:
x = ((-b + or - sqrt(b^2-4ac))/2a)
a=1, b=-13/2, c=-3
x = ((-(-13/2) + or - sqrt(-13/2^2 -4(1)(-42))/2(1))
x = (13/2 + sqrt(-13/2^2 + 168)/2 = + or - 9.667
you can do the math with your calculator, but I've shown you how to calculate the value of x; this is one way your problem can be solved. Notice that when your equation contains a variable to the power of 2, there will be two answers for the value of x. This formula is worth knowing! Good luck!
2006-10-01 11:16:59 · answer #2 · answered by ronw 4 · 0⤊ 0⤋
My learned colleague above is wrong. Why on Earth is he using the formula (and still gets the answer wrong), when the equation factorises very easily (insert Homer Simpson quote here).
If you are an honours student and you cannot solve an equation that eleven year olds are taught how to solve you are well and truly screwed.
X^2 - 13/2X - 42 = 0
(x + 4) (x -10.5)
x = -4 and x = 10.5
Check it for yourself.
2006-10-01 09:16:50 · answer #3 · answered by Andrew W 4 · 1⤊ 0⤋
Let me get this straight, you do "honours" geometry??????????
Man you need to get back to junior high.
this is,
x^2 - 6x = (1/2) x + 42
multiply throughout by 2 and you get,
2x^2 - 13x - 84 = 0
either this factorises or just complete the square.
2006-10-01 11:20:55 · answer #4 · answered by yasiru89 6 · 1⤊ 0⤋
x^2 -6x -.5x -42= 0
x^2 -6.5x - 42 = 0
2x^2 - 13x - 84 = 0
(x-10.5) (x+4) = 0
x= 10.5 or x=-4
2006-10-01 18:57:16 · answer #5 · answered by Anonymous · 0⤊ 0⤋
x^2-6x-1/2. x-42=0
x^2-13/2 . x-42=0
2x^2-13x-42=0
a=2
b=-13
c=-42
x1=(13+sqrt(169+336 )/4
x1=(13-sqrt(169+336 )/4
2006-10-01 08:46:45 · answer #6 · answered by iyiogrenci 6 · 0⤊ 1⤋
your screwed
2006-10-01 08:42:00 · answer #7 · answered by ? 2 · 0⤊ 2⤋
????????? dunno
2006-10-01 08:47:27 · answer #8 · answered by koolgal 2 · 0⤊ 1⤋