SOLUTION: Can someone please help with these few question step by step? I work them out,but it doesn't add up. 8x^2-64=0 x= 0.7x^2=175 x= 4.8x^2=8 x= 2.56x^2=20 x= x^2+8x=16

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Can someone please help with these few question step by step? I work them out,but it doesn't add up. 8x^2-64=0 x= 0.7x^2=175 x= 4.8x^2=8 x= 2.56x^2=20 x= x^2+8x=16       Log On


   

Question 966747: Can someone please help with these few question step by step? I work them out,but it doesn't add up.
8x^2-64=0 x=
0.7x^2=175 x=
4.8x^2=8 x=
2.56x^2=20 x=
x^2+8x=16 x=
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
8x^2-64=0
8x^2 = 64
x^2 = 8
x = +/- sqrt(8)
------------
0.7x^2=175
x^2 = 250
etc
------
4.8x^2=8 x=
Same as above
-----
2.56x^2=20 x=
Same as above
------
x^2+8x=16
x^2 + 8x - 16 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B8x%2B-16+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%288%29%5E2-4%2A1%2A-16=128.

Discriminant d=128 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-8%2B-sqrt%28+128+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%288%29%2Bsqrt%28+128+%29%29%2F2%5C1+=+1.65685424949238
x%5B2%5D+=+%28-%288%29-sqrt%28+128+%29%29%2F2%5C1+=+-9.65685424949238

Quadratic expression 1x%5E2%2B8x%2B-16 can be factored:
1x%5E2%2B8x%2B-16+=+%28x-1.65685424949238%29%2A%28x--9.65685424949238%29
Again, the answer is: 1.65685424949238, -9.65685424949238. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B8%2Ax%2B-16+%29