I do not know how to do this problem and would really appreciate anyone who might explain it to me.
x(2x-1)=45 it's a quadratic equation.. trying to find the diminsions of a shape.
Grace
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I do not know how to do this problem and would really appreciate anyone who might explain it to me.
x(2x-1)=45 it's a quadratic equation.. trying to find the diminsions of a shape.
Grace
Expand it out and subtract 45 from both sides.
It factors, so let's do that.
What two numbers when multiplied equal -90 and when added equal -1?
It is -90 because when we multiply the coefficient of x^2, 2, and the constant -45 we get -90. And the coefficient of x is -1.
Let's see... what could they be?
How about -10 and 9.
Group:
Factor out something common from each group:
See? What's in the parentheses is the same. That is imperative or it won't work.
There ya' go. See how to do them now?
Solving for x: 2x+9=0, x=-9/2
x-5=0, x=5
The solutions are x=-9/2 and 5.
It crosses the x-axis at -9/2 and 5.
If you have to find the vertex, use
Plug that back into the original quadratic to find the corresponding y coordinate.
But what do you mean 'the dimensions of a shape'?
It's a parabola if you graph it.
Thanks! What I meant by shape was, the problem asked me to find the dimensions of a shape, and I figured out the formula for it, I just didn't know how to slove the formula.
Oh, OK. I hope that helped. You could also just use the quadratic formula. That may be easier, but I like to factor if possible.
Yes it really did help. Thanks so much!
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