Find the sum of the areas of the shaded rectangles under the graph. Round to two decimal places. [Hint: The width of each rectangle is the difference between the x-values at its base. The height of each rectangle is the height of the curve at the left edge of the rectangle.] y 8- 7 6 5 y=4x 4 3 2 1 x 1 1.25 1.5 1.75 2 i square units