Question

[Baby Siêu Cute]

Tìm x : 

2^xx + 2^x+3 = 288

x + (x+1) + (x+2) + (x+3)+...+(x+30)=1240

Answer 1

[Tết]

\(2^x+2^{x+3}=288\)

\(\Rightarrow2^x+2^x.2^3=288\)

\(\Rightarrow2^x\left(1+2^3\right)=288\)

\(\Rightarrow2^x.9=288\)

\(\Rightarrow2^x=288:9\)

\(\Rightarrow2^x=32\)

\(\Rightarrow2^x=2^5\)

\(\Rightarrow x=5\)

Vậy \(x=5\)

\(x+\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+30\right)=1240\)

\(\Rightarrow x+x+1+x+2+x+3+...+x+30=1240\)

\(\Rightarrow x+x+x+...+x+1+2+3+...+30=1240\)

Từ \(1\rightarrow30\)có: \(\left(30-1\right):1+1=30\)( số )

\(\Rightarrow31.x+\left(30+1\right).30:2=1240\)

\(\Rightarrow31.x+31.15=1240\)

\(\Rightarrow31.x+465=1240\)

\(\Rightarrow31.x=1240-465\)

\(\Rightarrow31.x=775\)

\(\Rightarrow x=775:31\)

\(\Rightarrow x=25\)

Chúc bạn học tốt !!!

Answer 2

[Nguyễn Lương Phương Thảo]

x+(x+1)+(x+2)+....+(x+30)=1240
31 . x + (1 + 2 + 3 + 4 +...+ 29 + 30) = 1240
31 . x + 31.15 = 1240
31 . x = 1240 - 31.15
31 . x = 775
x = 775 : 31
x = 25

      Vậy x=25