Evaluate the foow∈g ∫eals.(a) <span class="katex-r" data-latex="displaystyle i∫_D ac{y}{1+x^2} dxdy"></span>, whe <span class="katex-r" data-latex="displaystyle D"></span> is enclosed by <span class="katex-r" data-latex="displaystyle y = st{x}"></span>, <span class="katex-r" data-latex="displaystyle y = 0"></span> and <span class="katex-r" data-latex="displaystyle x = 1"></span>.(b) <span class="katex-r" data-latex="displaystyle ∫_0^1 dx ∫_x^{2x} dy ∫