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\(a,2x\left(x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2x=0\\x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x\in\forall Z\\x=1\end{cases}}}\)
\(b,x\left(2x-4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\2x-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}}\)
\(c;\left(x+1\right)+\left(x+3\right)+...............+\left(x+99\right)=0\)
\(\Rightarrow\left(x+x+...........+x\right)+\left(1+3+............+99\right)=0\)
\(\Rightarrow50x+2500=0\)
\(\Rightarrow50x=-2500\)
\(\Rightarrow x=-50\)
2/
\(a;\left(x-3\right)\left(2y+1\right)=7\)
\(\Rightarrow\left(x-3\right);\left(2y+1\right)\inƯ\left(7\right)=\left\{\pm1;\pm7\right\}\)
Xét bảng
x-3 | 1 | -1 | 7 | -7 |
2y+1 | 7 | -7 | 1 | -1 |
x | 4 | 2 | 10 | -4 |
y | 3 | -4 | 0 | -1 |
Vậy...............................
\(b;xy+3x-2y=11\)
\(\Rightarrow x\left(y+3\right)-2y-6=11-6\)
\(\Rightarrow x\left(y+3\right)-2\left(y+3\right)=5\)
\(\Rightarrow\left(x-2\right)\left(y+3\right)=5\)
\(\Rightarrow\left(x-2\right);\left(y+3\right)\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)
Xét bảng'
x-2 | 1 | -1 | 5 | -5 |
y+3 | 5 | -5 | 1 | -1 |
x | 3 | 1 | 7 | -3 |
y | 2 | -8 | -2 | -4 |
Vậy................................
Anh gửi nhé. Chúc em học tốt
Tìm x biết:
20 – x – 11 = 20 – 11 + 77
x = 20 – 20 + 11 – 11 – 77
x = – 77
Vậy x = – 77
a) x -1/4 = -3/8 . 2/5
x - 1/4 = -3/20
x = -3/20 + 1/4
x = 1/10
b) x/126 = -7/24 . -6/11
x/126 = 7/44
\(\Rightarrow\)x = rỗng
X-1/4.x=6/11.(6/12+9/12+-4/12)
X-1/4.x=6/11.11/12
X-1/4.x=1/2
X.(1-1/4)=1/2
X.(4/4+-1/4)=1/2
X.3/4=1/2
X=1/2:3/4
X=1/2.4/3
X=2/3
Giai thich trong mot bai toan neu co hai dau x ta se ko tinh duoc trong bai toan nay x-25℅.x=6/11.(1/2+3/4+1/3) co hai dau x nen ta phai dua x ra ngoai lam h chung x dung mot minh se la x.1 khi ta bo x ra ngoai thi ben trong con 1-25℅ roi ta tinh ra sau do lam binh thuong
\(\frac{X}{126}=\frac{-7}{24}.\frac{-6}{11}\)
\(\frac{X}{126}=\frac{42}{264}\)
\(\frac{X}{126}=\frac{7}{44}\)
\(X=\frac{7}{44}.126=\frac{882}{44}=\frac{441}{22}\)
Vậy x = 441/22
\(\frac{x}{126}=\frac{-7}{24}.\frac{-6}{11}\)
\(\Rightarrow\frac{x}{126}=\frac{7}{44}\)
\(\Rightarrow x.44=126.7\)
\(\Rightarrow x.44=882\)
\(\Rightarrow x=882:44\)
\(\Rightarrow x=\frac{441}{22}\)
\(\frac{x}{126}=\frac{-7}{24}.\frac{-6}{11}\)
\(\Leftrightarrow\frac{x}{126}=\frac{7}{44}\)
\(\Leftrightarrow x.44=126.7\)
\(\Leftrightarrow x.44=882\)
\(\Leftrightarrow x=882:44\)
\(\Leftrightarrow x=\frac{441}{22}\)
x126=−724×−611
⇔x126=42264
⇔x126=744
⇔x=126×744
⇔x=126×744
⇔x=44122