Пишу сразу решение (
1) а^2*3 * a^3*5= a^6 * a^15= a^6+15= a^21
2)(x^2+3)^4=(x^5)^4=x^5*4=xx^20
3)((z^2*5)*z^3)^2= (z^10*z^3)^2= (z^10+3)^2= (z^13)^2= z^13*2=z^26
4)(b^2+3)^4= (b^5)^4=b^5*4=b^20
5)(c^3*4 * c^8 = c^12*c^8= c^12+8= c^20
6)(m^8+1)^3=(m^9)^3= m^9*3= m^27