Question

Алгебра! 7 класс.
Помогите

Answer 1

Решение:

1) $2.8 *5a=\frac{28}{10} *\frac{5}{1}a=\frac{140}{10}a=\frac{14}{1}a= 14a$;

2) $-3.5a*4=\frac{-35}{10} *\frac{4}{1}a = \frac{-35*4}{10*1} a=\frac{-140}{10}a=\frac{-14}{1}a= -14a$;

3) $3.6*0.8a=\frac{36}{10}*\frac{8}{10}a =\frac{36*8}{10*10}a=\frac{288}{100}a =2.88a$;

4) $-8a*(-12)=96a$;

5) $8x*(-3a)=-24ax$;

6) $3.5x*2y=\frac{35}{10} *\frac{2}{1}xy=\frac{35*2}{10*1}xy=\frac{70}{10}xy=\frac{7}{1}xy= 7xy$;

7) $-0.25y*8b=-\frac{1}{4}*\frac{8}{1} by=-\frac{1*8}{4*1}by=-\frac{8}{4}by=-\frac{2}{1} by = -2by$;

8) $\frac{3}{7} p*\frac{7}{9} q=\frac{3*7}{7*9}pq =\frac{21}{63}pq=\frac{1}{3} pq=\frac{pq}{3}$

Объяснение: