1. Упростите выражение: а)3ас∙5ав б) 10х∙9у∙(−7а)

Решение:
$\displaystyle \tt 3ac \times 5ab = \displaystyle \red 1\displaystyle \red5 { \displaystyle \red a}^{ \displaystyle \red 2} \displaystyle \red b \displaystyle \red c \\ \displaystyle \tt 10x \times 9y \times ( - 7a) = 90xy \times ( - 7a) = \displaystyle \red - \displaystyle \red 6 \displaystyle \red 3 \displaystyle \red 0 \displaystyle \red a \displaystyle \red x \displaystyle \red y$