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-79 - 9.(2x - 1)2 = -160
9.(2x - 1)2 = -79 - (-160)
9.(2x - 1)2 = 81
(2x - 1)2 = 81 : 9
(2x - 1)2 = 9
(2x - 1)2 = 32
\(\Rightarrow\) 2x - 1 = 3
2x = 3 + 1
2x = 4
x = 4 : 2
x = 2
Vậy x = 2
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x – 12 = 14
x = 14 +12
x = 26
b) 2x – 13 = 3.17
2x = 51 + 13
2x = 64
x = 64 : 2
x = 32
c) x – 43 = 2.18
x = 36 +43
x = 79
d) (x – 14).39 = 0
x – 14 = 0
x = 14
e) (13 – x).28 = 28
13 – x = 1
13 – x = 1
x = 13 – 1
x = 12
f) 22.(35 – x) = 22
35 – x = 1
x = 35 – 1
x = 34
g) x – 24 : 2 = 18
x – 12 = 18
x = 39
h) 400 + (275 – x) = 570
275 – x = 570 – 400
275 – x = 170
x = 275 – 170
x = 105
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x - 12 = 14 x = 14 + 12 x = 26
b) 2 x - 13 = 3 . 17 2 x = 51 + 13 2 x = 64 x = 64 : 2 x = 32
c) x - 43 = 2 . 18 x = 36 + 43 x = 79
d) x - 14 . 39 = 0 x - 14 = 0 x = 14
e) 13 - x . 28 = 28 13 - x = 28 : 28 13 - x = 1 x = 13 - 1 x = 12
f) 22 . 35 - x = 22 35 - x = 1 x = 35 - 1 x = 34
g) x - 24 : 2 = 18 x - 12 = 18 x = 39
h) 400 + 275 - x = 570 275 - x = 570 - 400 275 - x = 170 x = 275 - 170 x = 105
![](https://rs.olm.vn/images/avt/0.png?1311)
Câu 4:
a) \(\left(1267-86\right)-\left(267+14\right)\)
\(=1267-86-267-14\)
\(=900\)
b) \(\left(3900-278\right)-\left(80-178\right)-520\)
\(=3900-278-80+178-520\)
\(=3200\)
c) \(\left(2023-79+15\right)-\left(-79+15\right)\)
\(=2023-79+15+79-15\)
\(=2023\)
d) \(-329-\left(15-101\right)-\left(25-101\right)\)
\(=-329-15+101-25+101\)
\(=-167\)
Câu 5:
Trong 2 bạn, không có ai là người trả lời đúng vì \(100-\left(37-49+12\right)=100-37+49-12\)
\(#WendyDang\)
28 . 178 - 14 . 2 . 79 + 7.4
⇒ 28 . 178 - 28 . 79 + 28 . 1
⇒ 28 . ( 178 - 79 + 1 )
⇒ 28 . 100
⇒ 2800
28 \(\times\) 178 - 14 \(\times\) 2 \(\times\) 79 + 7 \(\times\) 4
= 28 \(\times\) 178 - 28 \(\times\) 79 + 28 \(\times\) 1
= 28 \(\times\) (178 - 79 + 1)
= 28 \(\times\) {(178 + 1) - 79)}
= 28 \(\times\) { 179 - 79}
= 28 \(\times\) 100
= 2800