SOLUTION: f(x)=2x^2+4x+5

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Question 380225: f(x)=2x^2+4x+5
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,
f(x)=2x^2+4x+5 y=intercept Pt(0,5)
the vertex form of a parabola, y=a%28x-h%29%5E2+%2Bk where(h,k) is the vertex
f(x)=2[(x^2 +2x} +5
f(x)=2[(x+ 1)^2 -1} +5
f(x)=2(x+ 1) -2 + 5
f(x)=2(x+ 1)+3
vertex Pt(-1,3), parabola opens upward (a=2 and is > than zero)
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-4+%2B-+sqrt%28-24+%29%29%2F%284%29+
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B4x%2B5+=+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=%284%29%5E2-4%2A2%2A5=-24.

The discriminant -24 is less than zero. That means that there are no solutions among real numbers.

If you are a student of advanced school algebra and are aware about imaginary numbers, read on.


In the field of imaginary numbers, the square root of -24 is + or - sqrt%28+24%29+=+4.89897948556636.

The solution is

Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B4%2Ax%2B5+%29