# Proper Methods

I have this equation. 135=w(w+12)
Would random plugging in numbers into w effective? If not, please help me out... I know how to get to the answer i just need a better grasp on methods

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This is a volume equation from your other post and it is not quite correct yet. Once you get the equation correct, I can help you solve it.

Homework Helper
I have this equation. 135=w(w+12)
Would random plugging in numbers into w effective? If not, please help me out... I know how to get to the answer i just need a better grasp on methods
You mean, you need to solve for w? In that case, do you know how to find the roots of a quadratic equation?

here i go...
w^2+12W-135= 0
then blah blah blah quadratic formula.

cristo
Staff Emeritus

Your equation is not correct; it should be a cubic. The method I suggested to you regarding a different cubic equation was not simply "randomly substitute numbers." You make an educated guess as to what the value of w could be (note, it must be a factor of 135) and then see if it solves the equation.

Wait a minute this all can be cleared by one question. Is it possible to do a quadratic formula in a cubic equation? I know Im not at my full brain capacity today...

cristo
Staff Emeritus
Wait a minute this all can be cleared by one question. Is it possible to do a quadratic formula in a cubic equation? I know Im not at my full brain capacity today...
Is a cubic equation a quadratic equation?
Thus, can we use the quadratic equation to solve it?

I'm gonna leave this to someone else now, since I don't think you're reading my posts; and if you are, you're definitely not thinking about the questions and points I'm posing to you.

I've been at this question for 2 hours now... I just don't comprehend. Well here i go if i don't get this right this time I'm dropping calculas.
V=LW^2
135=(w+12)w^2
0=(w^2+12w-135)W
Am i right so far?