Question

Using benchmarks, what is the approximate value of each?

Answer 1

For a 7*7=49 so sqrt(49)=7
6*6=36 so sqrt(36)=6

and since sqrt(x) is am increasing function then
6 < sqrt(42) <7

you do the same for b but with 4 values :
like 4*4*4= 64
and 3*3*3=27