Question

Question #23e44

Answer 1

It is explained below

Explanation:

When substitution is done for x, the differential 'x' is converted to the substituted variable. Like when a substitution say, `x= tan theta` is used , dx would then convert to `sec^2 theta d theta`. Thus after sustitution there is no dx in the integrand as all 'x' get converted to `theta`. It can be looked upon as follows also

x= tan `theta` then `dx/(d theta) = sec^2 theta`

Or, `dx= sec^2 theta d theta`