From my hand and Wolfram alpha calculation, it becomes 16826.4. I know how to take a integral if both integrals are from exact numbers using ... ... <看更多>

take x and y one by one, first we fix x, then check what value of y would be. as the graph says, when x is fixed, y is from x/4 to 3x/4. so the integral is. ... <看更多>