Объяснение:

4. (5х^2 +6х-3)-(2х^2 -3х-4)=5х^2 +6х-3-2х^2 +3х+4=3х^2 +9х+1

5. (4^6 •2^9)/32^4=((2^2)^6 •2^9)/(2^5)^4=(2^(2•6+9))/2^(5•4)=2^(12+9)•2^(-20)=2^(21-20)=2^1=2

(2 2/3)^5 •(3/8)^6=(8/3)^5 •(3/8)^6=8^5 •3^(-5) •3^(6) •8^(-6)=8^(5-6) •3^(-5+6)=8^(-1) •3^1=3/8=0,375

6.125а^6 •b^3 •(-0,2a^2 •b^4)^3=5^3 •a^6 •b^3 •(-1/5)^3 •a^(2•3) •b^(4•3)=5^3 •a^6 •b^3 •(-5)^(-3) •a^6 •b^12=-5^(3-3) •a^(6+6) •b^(3+12)=-5^0 •a^12 •b^15=-1 •a^12 •b^15=-а^12 •b^15