Question

[daohuyentrang]

TINH SO NGUYEN N

a,3⁴<1/9.27n<3¹⁰

b,25<5ⁿ:5<625

c,5.25ⁿ=125²

d, 3²+6:3^n-1==7.3⁶

Answer 1

[$๖ۣۜN๖ۣۜE๖ۣۜV ๖ۣۜE ๖ۣۜR $ ^^๖ۣۜG๖ۣۜ...]

a)=3^4<3.n<3^10

=>n=4;5;6;7;8;9

b)5^2<5^n-1<5^4

=>n-1=3=>n=4

c)5.5^2n==5^6

=>5^2n+1=5^6

=>n=7/2