# 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

## Answers and Replies

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?

Answer these and the answer to your question will be obvious.

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?