Question

5^x+5^x+1=150

Answer 1

5^x + 5^x + 1 = 150

=> 5^x . ( 1 + 5 ) = 150

=> 5^x . 6 = 150

=> 5^X = 150 : 6

=> 5^x = 25

=> 5^x = 5^2

=> x = 2

Answer 2

\(5^x+5^{x+1}=150\)

\(\Rightarrow5^x+5^x.5=150\)

\(\Rightarrow5^x\left(5+1\right)=150\)

\(\Rightarrow5^x=150:6\)

\(\Rightarrow5^x=25\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

Answer 3

biết 1²+2²+3²+...+14²+15²=1240

Tính A=1²+3²+6²+9²+...+42²+45²