(x^h*y^k*b^c)^5

Can someone solve this quick please it’s solving polynomials!

Ineed with this problem 21 show steps

Is the number 128.439 a rational number

To find the inverse of a number a, one can use the equation f(c) = a-1/c=0 where c is the inverse of a use the secant method of finding roots of equations to find the inverse of a = 2.5 ,er = 0.001%