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=>(x-2023)[(x-2023)^21-1]=0
=>x-2023=0 hoặc x-2023=1
=>x=2023 hoặc x=2024
a, 7\(x\).(2\(x\) + 10) =0
\(\left[{}\begin{matrix}x=0\\2x+10=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=0\\2x=-10\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
Vậy \(x\in\) {-5; 0}
b, -9\(x\) : (2\(x\) - 10) = 0
9\(x\) = 0
\(x\) = 0
c, (4 - \(x\)).(\(x\) + 3) = 0
\(\left[{}\begin{matrix}4-x=0\\x+3=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
Vậy \(x\in\) {-3; 4}
1. Giải:
Do \(5x+13B\in\left(2x+1\right)\Rightarrow5x+13⋮2x+1.\)
\(\Rightarrow2\left(5x+13\right)⋮2x+1\Rightarrow10x+26⋮2x+1.\)
\(\Rightarrow5\left(2x+1\right)+21⋮2x+1.\)
Do 5(2x+1)⋮2x+1⇒ Ta cần 21⋮2x+1.
⇒ 2x+1 ϵ B(21)=\(\left\{1;3;7;21\right\}.\)
Ta có bảng:
2x+1 | 1 | 3 | 7 | 21 |
x | 0 | 1 | 3 | 10 |
TM | TM | TM | TM |
Vậy xϵ\(\left\{0;1;3;10\right\}.\)
2. Giải:
Do (2x-18).(3x+12)=0.
⇒ 2x-18=0 hoặc 3x+12=0.
⇒ 2x =18 3x =-12.
⇒ x =9 x =-4.
Vậy xϵ\(\left\{-4;9\right\}.\)
3. S= 1-2-3+4+5-6-7+8+...+2021-2022-2023+2024+2025.
S= (1-2-3+4)+(5-6-7+8)+...+(2021-2022-2023+2024)+2025 Có 506 cặp.
S= 0 + 0 + ... + 0 + 2025.
⇒S= 2025.
\(x+\left(x+1\right)+\left(x+2\right)+...+2023+2024=2024\)
\(\Rightarrow2023x+4090506=2024-2024-20232023\)
\(\Rightarrow x+4090506=-2023\)
\(\Rightarrow2023x=-2023-4090506\)
\(\Rightarrow2023x=-4092529\)
\(\Rightarrow x=-2023\).
Lời giải:
$2^x+2^{x+1}+2^{x+2}+...+2^{x+2019}=2^{x+2023}-8$
$2^x(1+2+2^2+...+2^{2019})=2^{x+2023}-8$
Xét:
$A=1+2+2^2+...+2^{2019}$
$2A=2+2^2+2^3+...+2^{2020}$
$\Rightarrow A=2A-A=2^{2020}-1$
Khi đó:
$2^x.A=2^{x+2023}-8$
$2^x(2^{2020}-1)=2^{x+2023}-2^3$
$2^x(2^{2023}-2^{2020}+1)-2^3=0$
$2^x(2^{2020}.7+1)=2^3$
$x$ ra số sẽ khá xấu. Bạn coi lại.
\(P=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{2021.2023}\)
\(2P=\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{3}{5.7}+...+\dfrac{2}{2021.2023}\)
\(2P=\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{2021}-\dfrac{1}{2023}\)
\(2P=\dfrac{1}{1}-\dfrac{1}{2023}\)
\(P=\dfrac{2022}{2023}:2\)
\(P=\dfrac{1011}{2023}\)
\(=>P=1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{2021}-\dfrac{1}{2023}\)
\(P=1-\dfrac{1}{2023}=\dfrac{2023}{2023}-\dfrac{1}{2023}=\dfrac{2022}{2023}\)
\(x.P=\dfrac{2022}{2023}=>x=P:\dfrac{2022}{2023}=\dfrac{2022}{2023}:\dfrac{2022}{2023}=1\)
\(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{x\left(x+1\right)}=\dfrac{2022}{2023}\)
\(\Rightarrow1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
\(\Rightarrow1-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
\(\Rightarrow\dfrac{1}{x+1}=1-\dfrac{2022}{2023}\)
\(\Rightarrow\dfrac{1}{x+1}=\dfrac{1}{2023}\)
\(\Rightarrow x+1=2023\)
\(\Rightarrow x=2022\)
Vậy x = 2022
#kễnh
\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{x.\left(x+1\right)}\)
= \(\dfrac{2-1}{1.2}+\dfrac{3-2}{2.3}+...+\dfrac{x+1-x}{x.\left(x+1\right)}\)
= \(\dfrac{2}{1.2}-\dfrac{1}{1.2}+\dfrac{3}{2.3}-\dfrac{2}{2.3}+...+\dfrac{x+1}{x.\left(x+1\right)}-\dfrac{x}{x.\left(x+1\right)}\)
= \(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}\)
= \(1-\dfrac{1}{x+1}\) =\(\dfrac{2022}{2023}\)
= \(\dfrac{2023}{2023}-\dfrac{1}{x+1}=\dfrac{2022}{2023}\)
⇒ \(x+1=2023\)
\(x=2023-1=2022\)
a) \(27\cdot75+25\cdot27-150\cdot2023^0\)
\(=27\cdot\left(75+25\right)-150\cdot1\)
\(=27\cdot100-150\)
\(=2700-150\)
\(=2550\)
b) \(3^x+3^{x+1}+16\cdot4=2^2\cdot5^2\)
\(\Rightarrow3^x+3^x\cdot3=100-64\)
\(\Rightarrow3^x\cdot\left(1+3\right)=36\)
\(\Rightarrow3^x\cdot4=36\)
\(\Rightarrow3^x=36:4\)
\(\Rightarrow3^x=9\)
\(\Rightarrow3^x=3^2\)
\(\Rightarrow x=2\)
`@` `\text {Ans}`
`\downarrow`
`x(x-2023) = 0`
`=>`
`TH1: x = 0`
`TH2: x - 2023 = 0`
`=> x = 0 + 2023`
`=> x = 2023`
Vậy, `x \in {0; 2023}.`
x.(x - 2023) = 0
⇒ x = 0 hoặc x - 2023 = 0
*) x - 2023 = 0
x = 0 + 2023
x = 2023
Vậy x = 0; x = 2023