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A rectangular picture is 12 by 16 inches. If a frame of uniform width contains an area of 165 square inches, what is the quadratic equation that represents this problem?

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Answer:

The quadratic equation that represents this problem is

4x² + 56x - 165 = 0

Explanation:

The dimensions of the picture are 16 length and 12 width both in inches

The area of the picture without frame = 16 x 12 = 192 square inches

Let the frame have a width of x inches. The frame surrounds the picture on both sides of the length and both sides of the breadth


Then the length with the frame = x + 16 + x = 2x + 16 inches

The width of the frame = x + 12 + x = 2x + 12 inches

The area of the painting with the frame
= (2x + 16)(2x + 12)

Using the FOILmethod to multiply these two expressions we get
(2x + 16)(2x + 12) = (2x)(2x) + 2x(12) + 16(2x) + 16 x 12

= 4x² + 24x + 32x + 192

= 4x² + 56x + 192

The area of the frame by itself is the area with frame - area of picture alone

Area of frame = 4x² + 56x + 192 - 192

=> 4x² + 56x

We are given the area of frame is 165 square inches
Hence we get
4x² + 56x = 165

To represent as a quadratic equation move 156 from the right side to the left side to get 0 on the right side

4x² + 56x - 165= 0

ANSWER

User Spycho
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