Find the uniform width of the frame.

Question

A rectangular canvas picture measures 5 by 7 inches. The canvas is mounted inside a frame of uniform width, increasing the total area covered by both canvas and frame to 63 square inches. Find the uniform width of the frame.

Answer 1

85(7) = 35

(5+2x)(7+2x) = 63 = an additional 63-35 = 28 square inches

4x^2 +24x +35 = 63

4x^2 +24x = 28

x^2 +6x = 28/4 = 7

(x+3)^2 = 7+9 = 16

x+3 = sqr16 = 4

x = -3 + 4 = 1 inch