The x-axis and the three lines x = 1, x = 4 and y = mx + 4 form a trapezoid. If the area of the trapezoid is 7, then what is m?
Here's the set-up.
So in the sketch, our line should have negative slope, but who knew? Well, OK, OK, we could have known. Suppose we had a rectangle, then m = 0, and b1 = m + 4 = 4. So the area of the rectangle would be 3 x 4 = 12, which is bigger than the area of the trapezoid. So m is negative already. Sheesh.