(16a^36b^2)^1/2

Please help and explain if can do

That can be reduced to:

Step-by-step explanation:

What you need to do here is factor any perfect squares out of the out of the expression.  That includes 16, a² and b².  If you pull those out of the radical, they become 4, a and be respectively, leaving 6a inside the radical:

or you can express that also as:

a reflection across the x axis and a 90 degree rotation left and right.