SOLUTION: PLEASE HELP ME!! The area of a rectangle of length x is given by 3x^2 + 5x. Find the width of the rectangle.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: PLEASE HELP ME!! The area of a rectangle of length x is given by 3x^2 + 5x. Find the width of the rectangle.      Log On


   

Question 75139: PLEASE HELP ME!!
The area of a rectangle of length x is given by 3x^2 + 5x. Find the
width of the rectangle.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Since the area is:
A=L%2Aw we can solve for w
w=A%2FL
Now lets plug in our values
w=%283x%5E2%2B5x%29%2Fx plug in A=3x%5E2%2B5x and L=x
w=3x%5E2%2Fx%2B5x%2FxBreak up the fraction into two fractions
w=3x%5E%28cross%282%29%29%2Fcross%28x%29%2B5%2Across%28x%2Fx%29 Divide like terms.
w=3x%2B5
So the width is w=3x%2B5


Check:
If we multiply L and w we should get A
A=L%2Aw
A=x%283x%2B5%29Plug in values for w and L
A=3x%5E2%2B5x%29 So our answer works