Approximate the value of the given integral by completing parts (a) and (b) below. (a) Use the trapezoidal rule, using n = 4. (b) Check by direct integration. J 3x dx 0 (a) Use the trapezoidal rule to approximate the integral. 3 x7 dx my 0 (Type an integer or a decimal.) (b) Find the exact value of the integral by integration. 3x dx = 0 (Type an integer or decimal rounded to two decimal places as as needed