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a)3-[17-x]=289-325
[17-x]=3-(289-325)
[17-x]=3-(-36)
[17-x]=39
x=17-39
x=-22
b)25-[x+5]=-415-[15-415]
25-[x+5]=-415+400
25-[x+5]=-15
[x+5]=25+15
[x+5]=40
x=40-5
x=35
a)-Ix-3I+16=4
-Ix-3I=4-16
-Ix-3I=-12
-IxI=-12+3
-IxI=-9
x=-9
b)3-(17-x)=289-(36+289)
3-(17-x)=289-325
3-(17-x)=-36
(17-x)=3-(-36)
(17-x)=39
x=17-39
x=-22
c)25-(x+5)=415-(15-415)
25-(x+5)=415-(-400)
25-(x+5)=815
(x+5)=25-815
(x+5)=-790
x=(-790)-5
x=-795
d)34+(21-x)=(3747-30)-3746
34+(21-x)=3717-3746
34+(21-x)=-29
31+x=21-(-29)
31+x=50
x=50-31
x=19
1,
a) |x| + |y + 1| =0
Ta có: |x| \(\ge\) 0 (Với x \(\in\) Z)
|y + 1| \(\ge\) 0 (Với y\(\in\) Z)
\(\Rightarrow\) |x| + |y + 1| \(\ge\) 0
Dấu "=" xảy ra (=):
\(\left\{\begin{matrix}\left|x\right|=0\\\left|y+1\right|=0\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=0\\y+1=0\end{matrix}\right.\Rightarrow}\left\{\begin{matrix}x=0\\y=0-1\end{matrix}\right.\Rightarrow}\left\{\begin{matrix}x=0\\y=-1\end{matrix}\right.\)
Vậy x = 0; y = -1
b) (2 - x)4 = 81
\(\Rightarrow\) (2 - x)4 = 34 = (-3)4
\(\Rightarrow\) \(\left[\begin{matrix}2-x=3\\2-x=-3\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=2-3\\x=2-\left(-3\right)\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=-1\\x=5\end{matrix}\right.\)
Vậy: x \(\in\) {-1; 5}
c) |x - 1| + (-3) = 17
\(\Rightarrow\) |x - 1| = 17 - (-3)
\(\Rightarrow\) |x - 1| = 20
\(\Rightarrow\left[\begin{matrix}x-1=-20\\x-1=20\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=-20+1\\x=20+1\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=-19\\x=21\end{matrix}\right.\)
Vậy: x \(\in\) {-19; 21}
d) 3 - (17 - x) = 289 - (36 + 289)
\(\Rightarrow\) 3 - (17 - x) = 289 - 36 - 289
\(\Rightarrow\) 3 - (17 - x) = 289 - 289 - 36\(\Rightarrow\) 3 - (17 - x) = 0 - 36
\(\Rightarrow\) 3 - (17 - x) = -36 \(\Rightarrow\) 17 - x = 3 - (-36) \(\Rightarrow\) 17 - x = 39 \(\Rightarrow\) x = 17 - 39 \(\Rightarrow\) x = -22 Vậy: x = -22 e) 25 - (x + 5) = -415 - (15 - 415) \(\Rightarrow\) 25 - (x + 5) = -415 - 15 + 415 \(\Rightarrow\) 25 - (x + 5) = (-415 + 415) - 15 \(\Rightarrow\) 25 - (x + 5) = 0 - 15 \(\Rightarrow\) 25 - (x + 5) = -15 \(\Rightarrow\) x + 5 = 25 - (-15) \(\Rightarrow\) x + 5 = 40 \(\Rightarrow\) x = 40 -5 \(\Rightarrow\) x = 35 Vậy: x = 35 f) 34 + (21 - x) = (3747 - 30) - 3746 \(\Rightarrow\) 34 + (21 - x) = 3747 - 30 - 3746 \(\Rightarrow\) 34 + (21 - x) = 3747 - 3746 - 30 \(\Rightarrow\) 34 + (21 - x) = 1 - 30 \(\Rightarrow\) 34 + (21 - x) = -29 \(\Rightarrow\) 21 - x = -29 - 34 \(\Rightarrow\) 21 - x = -63 \(\Rightarrow\) x = 21 - (-63) \(\Rightarrow\) x = 84 Vậy: x = 84
a) 3 - (17 - x) = 289 - (36 + 289)
3 - (17 - x) = 289 - 325
3 - (17 - x) = -36
17 - x = -36 - 3
17 - x = -39
x = -39 + 17
x = -22
b) 25 - (x + 5) = -415 - (15 - 415)
25 - (x + 5) = -415 - 400
25 - (x + 5) = -15
- (x + 5) = -15 - 25
- (x + 5) = -40
x + 5 = 40
x = 40 - 5
x = 35
c) 34 + (21 - x) = (3747 - 30) - 3746
34 + 21 - x = (3747 - 30) - 3746
55 - x = -29
x = 55 - (-29)
x = 84
1/ a/ \(3-\left(17-x\right)=289-\left(36+289\right)\)
\(3-\left(17-x\right)=-36\)
\(17-x=3-\left(-36\right)\)
\(x=17-39=-22\)
b/ \(25-\left(x+5\right)=415-\left(15-415\right)\)
\(25-\left(x+5\right)=815\)
\(x+5=25-815\)
\(x=\left(-790\right)-5=-795\)
c/ \(\left|x-7\right|+13=25\)
\(\left|x-7\right|=25-13=12\)
\(\left|x-7\right|\Rightarrow\left[{}\begin{matrix}x-7=12\\x-7=-12\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=19\\x=-5\end{matrix}\right.\)
Câu 2:
a) (a - 1) - (a - 3) = a - 1 - a + 3 = 2
b) (2 + b) - (b + 1) = 2 + b - b - 1 = 1