put the square roots in lowest terms

square root 20 and square root 150

20 = 4 * 5

20 = 2*2 * 5
so
sqrt(20) = 2 sqrt 5

150 = 10 * 15
150 = 2 * 5 * 5 * 3
150 = 5*5 * 6
sqrt (150) = 5 sqrt 6