1) x-12=(-8)+(-17)
    x-12=(-25)
    x      = (-25)+12
    x      = (-13)

mk chịu thôi

mk dốt toán lắm

Tôi chịu

c: \(S=13+13^2+13^3+\cdots+13^{2022}\)

=>\(13S=13^2+13^3+\cdots+13^{2023}\)

=>13S-S=\(13^2+13^3+\cdots+13^{2023}-13-13^2-\cdots-13^{2022}\)

=>12S=\(13^{2023}-13\)

=>12S+13=\(13^{2023}\)

=>\(13^{2x+1}=13^{2023}\)

=>2x+1=2023

=>2x=2022

=>x=1011

d: \(S=13+13^2+13^3+\cdots+13^{2022}\)

\(=\left(13+13^2\right)+\left(13^3+13^4\right)+\cdots+\left(13^{2021}+13^{2022}\right)\)

\(=13\left(1+13\right)+13^3\left(1+13\right)+\cdots+13^{2021}\left(1+13\right)=14\left(13+13^3+\cdots+13^{2021}\right)\) ⋮14

b: Ta có: \(S=13+13^2+\cdots+13^{2022}\)

\(=\left(13+13^2\right)+\left(13^3+13^4+13^5+13^6\right)+\left(13^7+13^8+13^9+13^{10}\right)+\cdots+\left(13^{2019}+13^{2020}+13^{2021}+13^{2022}\right)\)

\(=\left(13+169\right)+13^3\left(1+13+13^2+13^3\right)+13^7\left(1+13+13^2+13^3\right)+\cdots+13^{2019}\left(1+13+13^2+13^3\right)\)

\(=182+\left(1+13+13^2+13^3\right)\left(13^3+13^7+\cdots+13^{2019}\right)\)

\(=2+180+2380\left(13^3+13^7+\cdots+13^{2019}\right)\)

=>S chia 10 dư 2

=>S có tận cùng là 2

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Tham khảo:

Theo đề ta có:

X là số lẻ thì X ∈ \(\left\{125,127,129,131\right\}\)

mà X chia hết cho 5 nên X = 125

x =  125

c) \(\left|x\right|=3,5\Rightarrow\left[{}\begin{matrix}x=3,5\\x=-3,5\end{matrix}\right.\)

d) \(\left|x\right|=-2,7\Rightarrow x\in\varnothing\) 

l) \(\left|x+\dfrac{3}{4}\right|-5=-2\Rightarrow\left|x+\dfrac{3}{4}\right|=3\)

\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=3\\x+\dfrac{3}{4}=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3-\dfrac{3}{4}\\x=-3-\dfrac{3}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{9}{4}\\x=\dfrac{15}{4}\end{matrix}\right.\)

Đính chính câu l \(x=-\dfrac{15}{4}\) không phải \(x=\dfrac{15}{4}\)

k mik đã rùi làm

=> 133 x 69 = ( x - 5 ) x 91

=> 9177 = 91 x ( x - 5 )

=> x - 5 = 1311/13

=> x = 1376/13

(x + 5)2 = (x + 5)(x – 5)

⇔ (x + 5)2 - (x + 5)(x - 5) = 0

⇔ (x + 5)(x - 5 + x + 5) = 0

⇔ (x + 5).10 = 0

⇔ x + 5 = 0

⇔ x = -5

Vậy: x = -5