Explaining of (3/2 x^(1/2))^2 I haven't taken math in a while and in my textbook there's this part to a problem that I don't quite understand. It's where L = the integral 1 to 2 of the sqrt(1 + (3/2 x^(1/2))^2)dx and they use u substitution to get u = 1 + 9/4x, du = 9/4x. I'm stuck at how they got (3/2 x^(1/2))^2 to = 9/4x. 

$$\large\left(\frac32 x^{\frac12}\right)^2=\left(\frac32\right)^2\left(x^{\frac12}\right)^2=\frac94x^{\frac12\times2}=\frac94x$$
