The length of a rectangle is 2 feet less than three times the width. If the area of the rectangle is 40 square feet, find the dimensions.

Question

anonymous · Answer

A=L*W
A-Area
L-Length
W-Width

anonymous · Answer

L+2=3W

anonymous · Answer

Doesn't the 40 have something to do with the equation?

anonymous · Answer

A=(3W-2)*W=40
3W^2-2W=40

anonymous · Answer

3W^2-2W-40=0
w=4

anonymous · Answer

so L=10

anonymous · Answer

Can you elaborate more on how you got w

anonymous · Answer

$$ax ^{2}+bx+c=0$$

anonymous · Answer

$$x=\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }$$

anonymous · Answer

substitute to the formula, here we have W instead of x

anonymous · Answer

Is the first one you showed completing the square?

anonymous · Answer

nope, it's the condition for the second one formula

anonymous · Answer

whenever you have an equation of such kind, you will apply that formula to find x

anonymous · Answer

Oh okay got it. Your just putting it in descending order to do the quadratic formula

anonymous · Answer

i disregarded negative value for width, as width can not be negative

anonymous · Answer

Okay thanks