`-214-[(117-x)-314]=0`

`=> -214-(117-x-314)=0`

`=> -214-117+x+314=0`

`=> x-17=0`

`=> x=0+17`

`=> x=17`

\(-214-[\left(117-x\right)-314]\text{=}0\)

\(-214-\left(117-x-314\right)\text{=}0\)

\(-214-117+x+314\text{=}0\)

\(x-17\text{=}0\)

\(x\text{=}17\)

Yêu cầu đề bài là gì vậy bạn?

tính

Sửa đề:
\(A=2+2^2+2^3+2^4+...+2^{2014}\)
\(\Rightarrow2A=2^2+2^3+2^4+2^5+...+2^{2015}\)
\(\Rightarrow2A-A=\left(2^2+2^3+2^4+2^5+...+2^{2015}\right)-\left(2+2^2+2^3+2^4+...+2^{2014}\right)\)
\(\Rightarrow A=2^{2015}-2\)
Mà \(B=2^{2015}+1\)
\(\Rightarrow A< B\)

Ta có:
A = 2⁰ + 2¹ + 2² + 2³ +...+ 2²⁰¹⁷
=> 2A = 2¹ + 2² + 2³ +...+ 2²⁰¹⁷ + 2²⁰¹⁸
=> 2A - A = 2²⁰¹⁸ - 2⁰
=> A = 2²⁰¹⁸ - 1
Mà B = 2²⁰¹⁸ - 1
=> A = B

Vậy A=B

\(\left(-\dfrac{1}{6}\right)\cdot\dfrac{19}{4}\)
\(=-\dfrac{19}{24}\)

-1/6 . 19/4

=-2/12 . 57/12

=-114/12 = -19/2

chúc bạn học tốt
 

Ta có:
\(\left(\dfrac{3}{5}\right)^2< 1\)

\(1< \left(\dfrac{5}{3}\right)^2\)
Do đó \(\left(\dfrac{3}{5}\right)^2< \left(\dfrac{5}{3}\right)^2\)

a/\(-\dfrac{1}{6}+\left(-\dfrac{5}{8}+\dfrac{7}{6}\right)\)
\(=\left(-\dfrac{1}{6}+\dfrac{7}{6}\right)-\dfrac{5}{8}\)
\(=1-\dfrac{5}{8}\)
\(=\dfrac{8}{8}-\dfrac{5}{8}=\dfrac{3}{8}\)
b/\(\left(\dfrac{2}{5}\right)^2+5\dfrac{1}{2}\cdot\left(4,5-2\right)+\dfrac{2^3}{\left(-4\right)}\)
\(=\dfrac{4}{25}+\dfrac{11}{2}\cdot\dfrac{5}{2}+-\dfrac{2^3}{2^2}\)
\(=\dfrac{4}{25}+\dfrac{55}{4}+\left(-2\right)\)
\(=\dfrac{16}{100}+\dfrac{1375}{100}-\dfrac{200}{100}\)
\(=\dfrac{1191}{100}=11,91\)

bằng 239/ 210 nha

\(\left(-\dfrac{1}{15}\right)-\dfrac{15}{14}\)
\(=-\dfrac{14}{210}-\dfrac{225}{210}\)
\(=-\dfrac{239}{210}\)