Question

Use the laws of exponents and simplify $3^{-7}+3^{-4}$

Answer 1

$\left(A\right)3^{-7}+3^{-4}$

$={\left(\frac{1}{3}\right)}^7+{\left(\frac{1}{3}\right)}^4$

$=\frac{1}{3^7}+\frac{1}{3^4}\times \frac{3^3}{3^3}$

$=\frac{1+27}{3^7}$

$=\frac{28}{2187}$