r(x) = 3 ln(1.8)(1.8x); r(x) = 9.2, r(x) = 30

Question

find input value for r(x)=9.2, and r(x)=30

Answer 1

Assuming you mean 3ln(1.8)(1.8x) and not 3ln( (1.8)(1.8x) )

r(x) = 9.2

9.2 = 3ln(1.8)(1.8x)

1.8x = 9.2/(3ln(1.8))

x = 9.2/5.4ln(1.8)

x = about 1.001

.

r(x) = 30

x = 30/5.4ln(1.8)

x = about about 3.265