Evaluate: \(\int_{2}^{5}\frac{\sqrt{x}}{\sqrt{x}+\sqrt{7-x}}\,dx\)
Q.2 (B) (ii) Evaluate: \(\int_{2}^{5}\frac{\sqrt{x}}{\sqrt{x}+\sqrt{7-x}}\,dx\)
Q.2 (B) (ii) Evaluate: \(\int_{2}^{5}\frac{\sqrt{x}}{\sqrt{x}+\sqrt{7-x}}\,dx\)
Best answer
Answer: \(\frac{3}{2}\)
Let \(I=\int_{2}^{5}\frac{\sqrt{x}}{\sqrt{x}+\sqrt{7-x}}\,dx\) ... (1)
Using \(\int_a^b f(x)\,dx=\int_a^b f(a+b-x)\,dx\) with \(a+b=7\):
\(I=\int_{2}^{5}\frac{\sqrt{7-x}}{\sqrt{7-x}+\sqrt{x}}\,dx\) ... (2)
Adding (1) and (2): \(2I=\int_{2}^{5}\frac{\sqrt{x}+\sqrt{7-x}}{\sqrt{x}+\sqrt{7-x}}\,dx=\int_2^5 1\,dx=[x]_2^5=3\).
\(\therefore I=\frac{3}{2}\).
Log in or create a free account to answer this question.