Simplify the following, giving your answer with a positive index: $2^2\times2^2$22×22
Simplify the following, giving your answer in index form: $3^9\times3^{10}$39×310.
Simplify the following, giving your answer in index form: $2^2\times2^3\times2^4$22×23×24.
Simplify the following, giving your answer in index form: $5^4\times5^3$54×53.