Answer 1

Let `I=∫_4^9 1/sqrtxdx`

`=∫_4^9 x^-(1/2)dx`

`=[x^(1/2)/(1/2)]_4^9=2[sqrtx]_4^9`

`=2(sqrt9-sqrt4)`

`=2(3-2)`

`therefore I=2`