Question

tìm x

\(5^x+5^{x+1}+5^{x+2}=775\)

Answer 1

5^x + 5^{x + 1} + 5^{x + 2} = 775

\(\Rightarrow\) 5^x + 5^{x + 1} + 5^{x + 2} = 5² + 5^{2 + 1} + 5^{2 + 2}

\(\Rightarrow\) x = 2

Answer 2

5^x + 5^x+1 + 5^x+2 = 775

5^x . 1 + 5^x . 5 + 5^x + 5² = 775

5^x . (1 + 5 + 25 ) = 775

5^x . 31 = 775

5^x = 775 : 31

5^x = 25

5^x = 5²

^x=2

Answer 3

5^x+5^x+1+5^x+2=775

Tacó:775=25+125+625=5²+5³+5⁴

=>5^x+5^x+1+5^x+2=5²+5³+5⁴

5^x+5^x+1+5^x+2=5²+

5²⁺¹+5²⁺²

=>x=2

Answer 4

\(5^x+5^{x+1}+5^{x+2}=775\)

\(\Rightarrow5^x.1+5^x.5+5^x.25=775\)

\(\Rightarrow5^x\left(1+5+25\right)=775\)

\(\Rightarrow5^x.31=775\)

\(\Rightarrow5^x=25\Rightarrow5^x=5^2\)

\(\Rightarrow x=2\)

Vậy.....