5. 3*(7х³+5х-4)++(21х²+5)*(3х+7)=21х³+15х-12+63х³+147х²+15х+35=

84х³+147х²+30х+23

формула (u*v)'=u'v+uv'

6. (u/v)'=(u'v-uv')/v²

((8х)(5-2х³)-(-6х²)(4х²+8))/(5-2х³)²=(40х-16х⁴+24х⁴+48х²)/(5-2х³)²=

(8х⁴+48х²+40х)/(5-2х³)²