\text { 3. [8 marks] Consider the integral } \int_{1}^{2} \sqrt{5-2 x} d x \text { . } (a) Using the trapezoidal rule with 4 subintervals, estimate the integral numerically.

(b) Find the integral exactly (using calculus and showing the working) and compare this with your numerical result by calculating the absolute value of the error.

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