How to prove that $3^{20}+4^{9}+6^{10}$ is composite? [closed]
How to prove that $3^{20}+4^{9}+6^{10}$ is composite? I tried to simplify it to a common exponent, I ended up with $9^{10} + \frac{4^{10}}{4} + 6^{10}$. Can anyone help?
Solution 1:
You are on the right track! Next step:
You very sneakily write it as $(3^{10}+2^{9})^2$.