The length of a rectangle is 9 inches more than 3 times the width. If the area of the rectangle is 210 square inches find the length and widths

Answer 1

w = 7

l = 30

Previously answered.

Answer 2

l = 3w + 9

A = 210 = lw

Substitute:

210 = (3w + 9) w

210 = 3w^2 + 9w

3w^2 + 9w - 210 = 0

Quadratic formula or factor. 3(w - 7)(w + 10) = 0

w = 7

(w = -10, ignore this answer as a width cannot be negative)

l = 30

Answer 3

W x (3w + 9) = 210

3w[squared] + 9w = 210

3w[sqared] + 9w - 210 = 0

3 (w squared + 3w -70 ) = 0

(W + 10)(w - 7) = 0

W = -10, w = 7

W cant equal - 10 because length cant be negative, so width must be 7.

3 times 7, + 9, = 30

30 x 7 = 210.

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