Question

Francine made a rectangular prism out of 40 cubic centimeters of clay. If its length is twice its width and its height is 1 centimeter more than its length, what is its length in centimeters? [Volume of a rectangular prism = length × width × height]
a)1
b)2
c)4
d)6
e)-7

Answer 1

V = 40 cm^3

L = 2*W
H = L + 1

Answer 2

V = L * W * H = 40

Answer 3

H = L + 1 and L = 2W so
H = 2W + 1

Answer 4

V = 40 = 2W * W * (2W+1)

Solve for W and use

H = 2*W + 1

Answer 5

L = 2W
H = 2W + 1
W = W

V = L x W x H

Answer 6

okay, so do i just plugging in the numbers for w in this? V = 40 = 2W * W * (2W+1)\

Answer 7

yes, solve for what W is

Answer 8

and if it equals 40 then thats the answer?

Answer 9

no, you can solve that for W, then use that number to find the Length L by using

L = 2*W

Answer 10

oh so i dont plug the answers into that to find w, i just solve it like a regular equation?

Answer 11

40 = 2W^2*(2W+1)

you will find W = 2 so
L = 2*W = 4

Answer 12

There is nothing to plug in, You have to use that equation to find what W is then use that W to find what the L is.

Answer 13

okay, i think i got it
is it l=4?

Answer 14

@DanJS

Answer 15

thank you

Answer 16

yep

Answer 17

Just read the question once or twice slow to get a feel for it, Then take it once sentence at a time, and try to translate it into equations.
"Length is twice the width" L = 2*W