18 mũ 2 bằng bao nhiêu
` 3. ` ` a) 3^7 . 27^5 . 81^3 ` ` =3^7 . (3^3)^5 . (3^4)^3 ` ` =3^7 . 3^{15} . 3^{12} ` ` =3^{34} ` ` b) 36^5 : 18^5 ` ` =(36:18)^5 ` ` =2^5=32 ` ` c) 24 . 5^5 + 5^2 . 5^3 ` ` =24 . 5^5 + 5^5 ` ` =5^5 . (24+1) ` ` =5^5 . 25 ` ` =5^5 .5^2=5^7 ` ` d)125^4 : 5^8 ` ` =(5^3)^4 : 5^8 ` ` =5^{12} : 5^8 ` ` =5^4=625 ` ` B4. ` ` a) 2^x . 4=16 ` ` => 2^x = 4=2^2 ` ` =>x=2 ` ` b)3^x . 3=243 ` ` =>3^x=81=3^4 ` ` =>x=4 ` ` c) 64 . 4^x=16^8 ` ` => 4^3 . 4^x =(4^2)^8 ` ` => 4^{x+3}=4^{16} ` ` =>x+3=16 ` ` =>x=13 ` ` d)2^x . 16^2=1024 ` ` =>2^x . (2^4)^2=2^{10} ` ` => 2^x . 2^8=2^{10} ` ` => 2^x = 2^{10}:2^8 ` ` =>2^x=2^2 ` ` =>x=2 ` Giải thích các bước giải: ` a^n =a.a.a....a(n ` thừa số ` a) ` ` a^n . b^n=(a.b)^n ` ` a^n : b^n=(a:b)^n `` ` (a^n)^m=a^{n.m} ` ` a^n . a^m=a^{n+m} ` ` a^n : a^m = a^{n-m} ` |