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Bài 1: Thực hiện phép tính
a) 165 - [ 120 - ( 9 - 4 )2 ]
b) 32 : { 160 : [ 300 - ( 175 + 21 . 5 ) ] }
c) 6 . 52 - 32 : 24 + 32
d) 42 .37 - 42 . 33 + 24
Bài làm:
a) 165 - [ 120 - ( 9 - 4 )2 ]
= 165 - [ 120 - 52 ]
= 165 - [ 120 - 25 ]
= 165 - 95
= 70.
b) 32 : { 160 : [ 300 - ( 175 + 21 . 5 ) ] }
= 32 : { 160 : [ 300 - ( 175 + 105) ] }
= 32 : { 160 : [ 300 - 280 ] }
= 32 : { 160 : 20 }
= 32 : 8
= 4.
c) 6 . 52 - 32 : 24 + 32
= 6 . 25 - 32 : 16 + 9
= 150 - 2 + 9
= 148 + 9
= 157.
d) 42 .37 - 42 . 33 + 24
= 16. ( 37 - 33)
= 16 . 4
= 64.
Bài 2: Tìm số tự nhiên x, biết:
a) 91-5 . ( 5 + x ) = 61
b) ( x + 34 ) - 40 = 28
c) 3 . ( x -2 ) + 150 = 240
d) 360 : ( x- 7) = 90
e) 2448 : [ 119 - ( x - 6) ] = 24.
Bài làm:
a) 91-5 . ( 5 + x ) = 61
5 . ( 5 + x) = 91 - 61
5. ( 5+ x) = 30
5 +x = 30 : 5
5 +x = 6
x = 6 - 5
x = 1.
b) ( x + 34 ) - 40 = 28
x+ 34 = 40 + 28
x+ 34 = 68
x = 68 - 34
x = 34.
c) 3 . ( x - 2 ) + 150 = 240
3 . ( x - 2 ) = 240 - 150
3 . ( x - 2 ) = 90
x - 2 = 90 : 3
x - 2 = 30
x = 30 + 2
x = 32.
d) 360 : ( x - 7 ) = 90
x - 7 = 360 : 90
x - 7 = 4
x = 4 + 7
x = 11.
e) 2448 : [ 119 - ( x - 6 ) ] = 24
[ 119 - ( x - 6 ) ] = 2448 : 24
[ 119 - ( x - 6 ) ] = 102
x - 6 = 119 + 102
x - 6 = 221
x = 221 + 6
x = 227.
********************************Chúc bạn học tốt***********************************
\(5x+2x=6^2-5^0\Leftrightarrow5x+2x=6^2-1\)
\(\Leftrightarrow5x-2x=36-1\Leftrightarrow5x-2x=35\Leftrightarrow x\left(5+2\right)=35\)
\(\Leftrightarrow7x=35\Leftrightarrow x=35:7\Leftrightarrow x=5\)
\(5x+x=150:2+3\Leftrightarrow5x+x=75+3\)
\(\Leftrightarrow5x+x=78\Leftrightarrow x\left(5+1\right)=78\Leftrightarrow x6=78\)
\(\Leftrightarrow x=78:6\Leftrightarrow x=13\)
a) 5x + 2x = 62 - 50
7x = 35 => x = 5
b) 5x + x = 150 : 2 + 3
6x = 78 => x = 13
c) 6x + x = 511 : 59 + 31
7x = 28 => x = 4
d) 5x + 3x = 36 : 33 x 4 + 12
8x = 120 => x = 15
e) 4x + 2x = 68 - 219 : 216
6x = 60 => x = 10
f) 5x + x = 39 - 311 : 39
6x = 30 => x = 5
g) 7x - x = 521 : 519 + 3 x 22 - 70
6x = 36 => x = 6
h) 7x - 2x = 617 : 615 + 44 : 11
5x = 40 => x = 8
Bài 1 :
a, Ta có : \(\left(-123\right)+\left|-13\right|+\left(-7\right)\)
= \(\left(-123\right)+13+\left(-7\right)=\left(-117\right)\)
b, Ta có : \(\left|-10\right|+\left|45\right|+\left(-\left|-455\right|\right)+\left|-750\right|\)
= \(10+45-455+750=350\)
c, Ta có : \(-\left|-33\right|+\left(-15\right)+20-\left|45-40\right|-57\)
= \(\left(-33\right)+\left(-15\right)+20-5-57=-90\)
a, 13.(x-9)=169
x-9 =169:13
x-9 =13
b, 230+[16+(x,-5)]=315.2\(^3\)
230+[16+(x,-5)]=2520
16+(x,-5)=2520-230
16+(x-5)=2290
x-5 =2290-16
x-5 =2274
x =2274+5
x =2279
c, 13x-3\(^2\)x=2003\(^1\)+1\(^{2016}\)
13x-9x=2004
(13-9)x=2004
4 . x=2004
x=2004:4
x=501
1) 2x . 4 = 128
2x = 128 : 4
2x = 32
2x = 25
=> x = 5
2) (2x + 1)3 = 125
(2x + 1)3 = 53
=> 2x + 1 = 5
2x = 5 - 1
2x = 4
x = 2
các bài khác bạn tự làm nha
(3 - x)(y + 4) = 0
=> 3 - x = 0 hoặc y + 4 = 0
=> x = 3 hoặc y = -4
kl_
260-709-181+(-360)
=(260-360)-(709+181)
=-100-890=-990
USE máy tính
a) \(\left(-5\right)\left(x-2\right)^2+360=\left(-150\right)\cdot3+43\cdot5\)
\(-5\cdot\left(x-2\right)^2+360=-235\)
\(-5\cdot\left(x-2\right)^2=-595\)
\(\left(x-2\right)^2=119\)
\(\left(x-2\right)^2=\left(\pm\sqrt{199}\right)^2\)
\(\Rightarrow\orbr{\begin{cases}x-2=\sqrt{119}\\x-2=-\sqrt{119}\end{cases}\Rightarrow\orbr{\begin{cases}x=\sqrt{119}+2\\x=2-\sqrt{119}\end{cases}}}\)
b) \(\left(x+5\right)-\left(3x+9\right)=-16\)
\(x+5-3x-9=-16\)
\(-2x-4=-16\)
\(-2x=-12\)
\(x=6\)
c) \(3\left(x+2\right)-\left(15-x\right)\cdot6=160+\left(-1\right)^{1005}\)
\(3x+6-90+6x=160-1\)
\(9x-84=159\)
\(9x=243\)
\(x=27\)
d) \(x\left(x-1\right)\left(x^2-4\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x\left(x-1\right)=0\\x^2-4=0\end{cases}\Rightarrow\orbr{\begin{cases}x=\left\{0;1\right\}\\x=\left\{2;-2\right\}\end{cases}}}\)