1) When multiply two monomials tho things need to remember
i) If both are plus then the product should be plus.
(+)(+)=(+)
ii) If one is plus and another is minus then the product should be minus.
(+)(-)=(-)
(-)(+)=(-)
i) If both are minus then product should be plus.
2) Law of exponence will be apply
\(a^{m} \times a^{n}=a^{m+n}\)
Example 1:
\(3x^{2}y^{3} \times -2xy^{4}\)
=\((3 \times -2).x^{2+1}.y^{3+4}\)
=\(-6x^{3}y^{7}\)
Example 2:
\(15a^{3}xy^{2} \times -\frac{1}{5}ax^{2}y^{3} \times \frac{1}{3}a^{2}y^{3}\)
=\((15 \times -\frac{1}{5} \times \frac{1}{3})a^{3+1+2}.x^{1+2}.y^{2+3+3}\)
=\(-1a^{6}x^{3}y^{8}\)