Definite Integration Question 197

Question: The line y = mx bisects the area enclosed by lines $ x=0,y=0 $ and $ x=3/2 $ and the curve $ y=1+4x-x^{2} $ . Then the value of m is

Options:

A) $ \frac{13}{6} $

B) $ \frac{13}{2} $

C) $ \frac{13}{5} $

D) $ \frac{13}{7} $

Show Answer

Answer:

Correct Answer: A

Solution:

[a] $ y=1+4x-x^{2}=5-{{(x-2)}^{2}} $ We have $ \int\limits_0^{3/2}{(1+4x-x^{2})dx=2\int\limits_0^{3/2}{mxdx}} $

$ =\frac{3}{2}+2( \frac{9}{4} )-\frac{1}{3}( \frac{27}{8} )=m.\frac{9}{4} $

On solving we get $ m=\frac{13}{6} $