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In Problems 1-5, let R be the region bounded by y = x² + 3, y = 2x, x = 0, and x = 4. Each problem will describe the cross sections of a solid that are perpendicular to the x-axis. Write an integral expression that can be used to find the volume of the solid (do not evaluate). 1) The cross sections are squares with one edge in R. 2) The cross sections are circles with the diameter in R. 3) The cross sections are equilateral triangles with one edge in R. 4) The cross sections are rectangles with the smaller edge in R. The larger edge of the rectangle is three times the smaller edge. 5) The cross sections are semicircles with the diameter in R.