2x = 112.5 - 0.5x^2
i know the final answer.. i just need to know how it is done. thanks
2007-12-04 07:14:07 · 9 answers · asked by whoopy_ass 1 in Science & Mathematics ➔ Mathematics
thank everyone.. havnt done quadratic in a while..
2007-12-04 07:24:48 · update #1
x^2 +4x - 225 =0
x= -2 +/-√229
2007-12-04 07:18:50 · answer #1 · answered by mbdwy 5 · 0⤊ 0⤋
Move the 1/2x^2 to the left along with the 112.5 to net you an equation of .5x^2 + 2x - 112.5 = 0. From there, you can use the quadratic equation where a=.5 , b=2, and c=112.5 .
If you dont know the quadratic equation, its
-b +_ sqrt( b^2 - 4ac ) / 2a. Now just plug and chug!
2007-12-04 15:19:00 · answer #2 · answered by Anonymous · 0⤊ 0⤋
2x = 112.5 - 0.5x²
0.5x² + 2x - 112.5 = 0
Divide both sides by 0.5 so x² has coefficient of 1:
x² + 4x - 225 = 0
Isolate the x terms:
x² + 4x = 225
Use the coefficient of x to complete the square:
x² + 4x + (4/2)²= 225+(4/2)²
x² + 4x + 4 = 229
(x+2)² = 229
x+2 = 屉229
x = -2屉229
x₊ = 13.133
x₋ = -17.133
2007-12-04 15:38:58 · answer #3 · answered by DWRead 7 · 0⤊ 0⤋
Write it as a quadratic:
0.5x^2 + 2x - 112.5 = 0
multiply by 2 to get rid of decimal:
x^2 + 4x - 225 = 0
You can use the quadratic formula to solve, as it does not factor.
that's it! :)
2007-12-04 15:17:50 · answer #4 · answered by Marley K 7 · 0⤊ 0⤋
0.5x^2 +2x - 112.5 = 0
5x^2 + 20x - 1125 = 0
x^2 + 4x - 225 = 0
solve for x using the quad formula
2007-12-04 15:20:03 · answer #5 · answered by norman 7 · 0⤊ 0⤋
Rearrange so it is in ax^2 + bx + c = 0 form:
0.5x^2 + 2x - 112.5 = 0
Use the quadratic formula: (-b +- square root(b^2 -4ac))/2a
a = .5
b = 2
c = -112.5
2007-12-04 15:22:11 · answer #6 · answered by fupastar 2 · 0⤊ 0⤋
i would multiply both sides of the equation by 2 to get rid of the nasty .5 's , next i would try to factor the formula x^2 + 4x -225 , since 225 = 15*15 i can not easily find the factors, so i then use the abc formula that gives the solution you already know.
2007-12-04 15:19:48 · answer #7 · answered by gjmb1960 7 · 0⤊ 0⤋
2x=112.5 - 0.5x^2
0.5x^2+2x-112.5=0
5x^2 + 20x -1125=0
x^2+4x-225=0
x^2 + 4x =225
x^2 +4x +2^2= 225+2^2
(x+2)^2 = 225+4
(x+2)^2=229
x+2=+(229)^1/2 or -(229)^1/2
x+2= 15.13 or x+2= -15.13
x=15.13 - 2 or x= -15.13 - 2
x=13.13 or x=-17.13
2007-12-04 15:30:41 · answer #8 · answered by naush 1 · 0⤊ 0⤋
you need to factor....FACTOR FACTOR FACTOR as I'm sure your teacher has repeated...
you need to get everything on one side of the equation..the left looks good...
.5x^2 + 2x -112.5=0
now, I think the best way to evaluate this would be to use the quadratic formula which is x=(-b+/-sqrt(b^2-4ac))/2a
a=.5
b=2
c= -112.5
solve for x
2007-12-04 15:17:45 · answer #9 · answered by Nostradamus is back squared 3 · 0⤊ 0⤋