Question

a9 × a18 =

Answer 1

you mean \[a^9\times a^{18} \] right?

Answer 2

Remember that exponents just mean to multiply a number by itself that many times. So you have 9 a's multiplying together and then 18 a's multiplying together. How many a's have you multiplied?

Answer 3

add the powers
a^m x a^n gives a^m+n

Answer 4

\[a^n*a^m=a^{n+m}\]

Answer 5

for example,
\[a^3*a^4 = (a*a*a)*(a*a*a*a) = a*a*a*a*a*a*a = a^7 = a^{3+4}\]

Answer 6

162