\(a,4^8.2^{20}=\left(2^2\right)^8.2^{20}=2^{16}.2^{20}=2^{16+20}=2^{36}\\ b,9^{12}.27^5.81^4=\left(3^2\right)^{12}.\left(3^3\right)^5.\left(3^4\right)^4=3^{24}.3^{15}.3^{16}=3^{24+15+16}=3^{55}\\ d,25^{20}.125^4=\left(5^2\right)^{20}.\left(5^3\right)^4=5^{40}.5^{12}=5^{40+12}=5^{52}\\ d,x^7.x^4.x^3=x^{7+4+3}=x^{14}\)
a: 4*8*2^20=2^2*2^3*2^20=2^25
b: 9^12*27^5*81^4=3^24*3^15*3^16=3^55
c: 25^20*125^4=5^40*5^12=5^52
d: =x^(7+4+3)=x^14