1. A) 410 x 815
B) 415 x 530
C) 2716 : 910
D) A= 723 x 542
1084
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`#3107.101107`
A.
`-7 + x = -3`
`=> x = -3 - (-7)`
`=> x = -3 + 7`
`=> x = 4`
Vậy, `x = 4`
B.
`-456 - x = 723`
`=> x = -456 - 723`
`=> x = -1179`
Vậy, `x = -1179`
C.
`-124-312 + x = -415`
`=> -436 + x = -415`
`=> x = -415 - (-436)`
`=> x = -415 + 436`
`=> x = 21`
Vậy, `x = 21`
D.
`-214+512-(-163)-x=-768- (-423)`
`=> 298 - (-163) - x = -345`
`=> 298 + 163 - x = -345`
`=> 461 - x = -345`
`=> x = 461 - (-345)`
`=> x = 461 + 345`
`=> x = 806`
Vậy, `x= 806.`
a: x-7=-3
=>x=-3+7=4
b: -456-x=723
=>x=-456-723=-1179
c: -124-312+x=-415
=>x-436=-415
=>x=21
d: -214+512-(-163)-x=-768-(-423)
=>461-x=-345
=>x=461+345=806
1)
`x^2 -144=0`
`<=> x^2 =144`
\(< =>\left[{}\begin{matrix}x=12\\x=-12\end{matrix}\right.\)
2)`
`2x^2 -72=0`
`<=>2x^2 =72`
`<=>x^2=36`
\(< =>\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)
3)
`5x^2 -125=0`
`<=> 5x^2 =125`
`<=>x^2 =25`
\(< =>\left[{}\begin{matrix}x=5\\x=-5\end{matrix}\right.\)
4)
`-x^2 +81=0`
`<=> x^2 -81=0`
`<=> x^2 =81`
\(< =>\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)
5)
`x(2x-18)=0`
\(< =>\left[{}\begin{matrix}x=0\\2x-18=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)
a) 542 x 7 + 542 x 2 + 542
= 542 x 7 + 542 x 2 + 542 x 1
= 542 x (7 + 2 + 1)
= 542 x 10
= 5420
b) (126 x 35 + 157 x 55) x (132 - 6 x 22)
= (126 x 35 + 157 x 55) x (132 - 132)
= (126 x 35 + 157 x 55) x 0 (Số bất kỳ nào nhân với 0 vẫn = 0)
= 0
c) 897 x 99 + 897
= 897 x 99 + 897 x 1
= 897 x (99 + 1)
= 897 x 100
= 89700
a) \(542.7+542.2+542\)
\(=542.\left(2+7+1\right)\)
\(=542.10=5420\)
b) \(\left(126.35+157.55\right).\left(132-6.22\right)\)
\(=13045.0=0\)
c) \(897.99+897\)
\(=897.\left(99+1\right)\)
\(=897.100=89700\)
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 = 84a) 415 x 7 - 415 x 5 + 415 x 8
= 415 x (7 - 5 + 8)
= 415 x 10
= 4150
b) 23 x 87 + 12 x 23 + 23
= 23 x 87 + 12 x 23 + 23 x 1
= 23 x (87 + 12 + 1)
= 23 x 100
= 2300
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
a. 4^10.8^15=2^20.2^30=2^50
b. 4^15.5^30=2^30.5^30=10^30
c. 27^16:9^10=3^48:3^20=3^28
a) 410.815 = (22)10 . (23)15 = 220 . 245 = 220+45 = 265
b) 415.530 = 415.(52)15 = 415.2515 = (4.25)15 = 10015
c) 2716:910 = (33)16:(32)10 = 348:320 = 348-20 = 328
d) \(A=\frac{72^3.54^2}{108^4}=\frac{\left(8.9\right)^3.\left(6.9\right)^2}{\left(12.9\right)^2}=\frac{8^3.9^3.6^2.9^2}{12^2.9^2}=\frac{8^3.9^3.6^2}{12^2}\)
\(=\frac{\left(2^3\right)^3.9^3.6^2}{\left(2.6\right)^2}=\frac{2^9.9^3.6^2}{2^2.6^2}=\frac{2^9.9^3}{2^2}=\frac{2^7.9^3}{2^0}=2^7.9^3=93312\)