Answer:
4x^2 + 156x - 1512 = 0
Explanation:
To determine the thickness of the border, we need to find the quadratic equation that represents the problem. The area of the table and border is the product of the width and length:
Area = (42 + 2x)(36 + 2x)
Expanding the expression, we get:
Area = 4236 + 2x36 + 2x42 + 2x2x
Simplifying further:
Area = 1512 + 72x + 84x + 4x^2
Area = 4x^2 + 156x + 1512
Comparing this equation to the given options, we see that:
4x^2 + 156x - 1512 = 0