Question

The length of a rectangle is 7 inches more than the width. The perimeter is 42 inches. Find the length and width

Answer 1

Cool, so for that rectangle, perimeter is 42. How do you find the perimeter?

Answer 2

Do you know the formula for finding the perimeter of an object?

Answer 3

i think its p=2l+2w

Answer 4

yeah, in this case for the rectangle, P = 2*length + 2*width. So you have values for the length and the width, right?

L = x + 7
W = x

Answer 5

Plug those values into the perimeter function, what does the equation look like after doing that?

Answer 6

my equation looks like this

42=2(7)+2w

42-14=28
which makes w = 14

then for L

14+7=21


am i right

Answer 7

Getting there, so the values you have for each dimension are actually variables - (x+7), and x

Therefore P = 2*L + 2*W becomes

L = x + 7
W = x
P = 2*(x+7) + 2*(x)

42 = 2*(x+7) + 2*(x)

Answer 8

Because there is only one variable, one unknown, that being 'x', we can easily then solve for it from the adjusted equation.

Answer 9

Does that make sense? Give that equation a shot, and solve for x.

Answer 10

x=7

Answer 11

Definitely! that's it, so L = ? and W = ?

Answer 12

Just have to do that last step and you're donw

Answer 13

Quite easy after finding x...

Answer 14

so w = 7 and l=14

Answer 15

Nice work

Answer 16

thanks