Answer:
[tex] {4a}^{4} \times {7a}^{5} \\ \\ = (4 \times 7)( {a}^{4} \times {a}^{5} ) \\ \\ = 28( {a}^{4} \times {a}^{5} )[/tex]
from law of indices:
[tex] {n}^{x} \times {n}^{y} = {n}^{(x + y)} [/tex]
therefore:
[tex] = 28 \{ {a}^{(4 + 5)} \} \\ \\ = 28 {a}^{9} [/tex]
