Question

An 8-inch-by-4-inch hole is cut from a

rectangular metal plate, leaving borders
of equal width x on all four sides. The
area of the metal that remains is 32 in².
The equation (8 + 2x)(4+2x) - 32 = 32
models the area of the plate. What is the
value of x, the frame width?

Answer 1

2 inches

Explanation:

The area of the metal plate can be calculated by subtracting the area of the hole from the area of the original plate. The area of the original plate is:

8 inches x 4 inches = 32 square inches

The area of the hole is:

8 inches x 4 inches = 32 square inches

So the area of the metal that remains is:

32 square inches - 32 square inches = 0 square inches

According to the equation given, we know that:

(8 + 2x)(4 + 2x) - 32 = 32

Expanding this equation we get:

32 + 16x + 8x + 4x^2 - 32 = 32

Simplifying and rearranging we get:

4x^2 + 24x - 32 = 0

Dividing both sides by 4 we get:

x^2 + 6x - 8 = 0

We can solve this quadratic equation by factoring:

(x + 4)(x - 2) = 0

So x = -4 or x = 2. Since the width of the frame cannot be negative, the only valid solution is x = 2.

Therefore, the frame width is 2 inches.