1) Tìm stn x biết
a)71.2-6.(2x+5)=105:103
b)(5x+34).68=69.34
c)12:(390:(5.102-(53+x.72)))=4
d)53.(3x+2):13=103:(135:134)
Tìm số tự nhiên x biết:
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
71.2 – 6.(2x+5) = 10 2
6.(2x+5) = 71.2 – 100
6.(2x+5) = 42
x = 1
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
5 x + 3 4 . 6 8 = 6 8 . 6 . 3 4
5 x + 3 4 = 6 8 . 6 . 3 4 : 6 8 = 6 . 3 4
5x = 6 . 3 4 - 3 4 = 5 . 3 4
x = 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
390:[5. 10 2 – ( 5 3 + x . 7 2 )] = 12:4 = 3
5. 10 2 – ( 5 3 + x . 7 2 ) = 390:3 = 130
5 3 + x . 7 2 = 5. 10 2 – 130 = 370
x . 7 2 = 370 – 5 3 = 245
x = 245: 7 2 = 5
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
5 3 .(3x+2):13 = 10 3 : 13
3x+2 = 10 3 : 13 : 5 3 .13 = 8
x = 2
Tìm số tự nhiên x biết:
a) 71 . 2 - 6 ( 2 x + 5 ) = 10 5 : 10 3
b) ( 5 x + 3 4 ) . 6 8 = 6 9 . 3 4
1: thực hiện phép tính
a)53-76-[-76-(-53)]
b)-87-12-(-48)+(-512)0
c)2+22+23+.....+2100
2 tìm xϵz,biết
a) (x-1)2=1
b)(x+1)3=-1
c)105-(135-7x):9=97
d)(x+7).(3-x)>0
e)3x-3-32=2.32
g)(2x2+1).(4-2x)=0
giúp nhoa
Bài 2:
a: =>x-1=1 hoặc x-1=-1
=>x=2 hoặc x=0
b: =>x+1=-1
hay x=-2
c: =>(135-7x):9=8
=>135-7x=72
=>7x=63
hay x=9
d: =>(x+7)(x-3)<0
=>-7<x<3
e: \(\Leftrightarrow3^{x-3}=18+9=27\)
=>x-3=3
hay x=6
f: =>4-2x=0
hay x=2
53*(3x+2):13=103:(135:134)
\(5^3.\left(3x+2\right):13=10^3:\left(13^5:13^4\right)\\ 125.\left(3x+2\right):13=1000:13\\ 125.\left(3x+2\right)=1000\\ 3x+2=1000:125\\ 3x+2=8\\ 3x=8-2\\ 3x=6\\ x=6:3\\ x=2\)
Tính hợp lí
A.35 x 34 + 35 x 38 + 65 x 75 + 65 x 45
B. 12x 53 + 53 x 172 - 53 x 84
C. 35 x 28 + 36 x 82 + 64 x 69 + 64 x 41
D. A = 1+2+3+...+100
E. B =17+19+...+101+103
G. D= 3x (12+13+14+15) + 3x(8+7+6+5)
A.35 x 34 + 35 x 38 + 65 x 75 + 65 x 45
Câu này không tính hợp lí được
B. 12x 53 + 53 x 172 - 53 x 84
= 53 x (12 + 172 - 84)
= 53 x 100
= 5300
C. 36 x 28 + 36 x 82 + 64 x 69 + 64 x 41
= 36 x (28+82) + 64 x (69+41)
= 36 x 110 + 64 x 110
= (36+64) x 110
= 100 x 110
= 11 000
D. A = 1+2+3+...+100
= (1+ 100) x 50
= 101 x 50
= 5050
E. B =17+19+...+101+103
= (103 +17) x [(103 - 17):2 + 1]
= 120 x 44
=5280
G. D= 3x (12+13+14+15) + 3x(8+7+6+5)
= 3 x (5+6+7+8+12+13+14+15)
= 3 x (20 x 4)
= 3 x 80
=240
a) 10320
b) 5300
c) 11000
d) 5050
e) 2460
g) 240
Bài 1:Tìm x,y thuộc Z biết:
a) 3x - 12 / 3y - 9 =68 / 51 và x - y = 5
b) 22x - 11 / 33 - 44y = 7 / 35 và x + y = 2
Bài 2: Rút gọn phân số:
a)1 . 3 . 5.....39 / 21 . 22 . 23.....40
b)54 . 107 - 53 / 53 . 107 + 54
c)135 . 269 - 133 / 134 . 269 + 135
Các bạn giúp mình nhanh nha! Mai phải nộp rồi
Tìm STN x, biết
1) (x + 2) - 2 = 0 2) (x + 3) + 1 = 7
3) (3x - 4) + 4 = 12 4) (5x + 4) - 1 = 13
5) (4x - 8) - 3 = 5 6) 3 + (x - 5) = 7
7) 8 - (2x - 4) = 2 8) 7 + (5x + 2) = 14
9) 5 - (3x - 11) = 1 10) 16 - (8x + 2) = 6
Lời giải:
1. $(x+2)-2=0$
$x+2=2$
$x=0$
2.
$(x+3)+1=7$
$x+3=7-1=6$
$x=6-3=3$
3.
$(3x-4)+4=12$
$3x-4+4=12$
$3x=12$
$x=12:3=4$
4.
$(5x+4)-1=13$
$5x+4=13+1=14$
$5x=14-4=10$
$x=10:5=2$
5.
$(4x-8)-3=5$
$4x-8=5+3=8$
$4x=8+8=16$
$x=16:4=4$
6.
$3+(x-5)=7$
$x-5=7-3=4$
$x=4+5=9$
7.
$8-(2x-4)=2$
$2x-4=8-2=6$
$2x=6+4=10$
$x=10:2=5$
8.
$7+(5x+2)=14$
$5x+2=14-7=7$
$5x=7-2=5$
$x=5:5=1$
9.
$5-(3x-11)=1$
$3x-11=5-1=4$
$3x=11+4=15$
$x=15:3=5$
10.
$16-(8x+2)=6$
$8x+2=16-6=10$
$8x=10-2=8$
$x=8:8=1$
Bài 1: Tìm x [GIÚPPPPPPPPPPPPPPPPPPP]
1) 5 – (10 – x) = 7
2) - 32 - (x – 5) = 0
3) -12 + (2x – 9) + x= 0
4) 11 + (15 - x) = 1
5) 4 - (27 - 3) = x - (13 - 4)
6) 8 - (x - 10) = 23 - (- 4 +12)
7) 105 – 5(10 – 5x) = -20
8) (x -1)(8-2x)(3x+123) = 0
9) (x2 - 25)(x+ 10) = 0
10) x(x2+5) = 0
\(1\)) \(5-\left(10-x\right)=7\)
\(10-x=5-7\)
\(10-x=-2\)
\(x=10-\left(-2\right)\)
\(x=12\)
\(2\)) \(-32-\left(x-5\right)=0\)
\(x-5=-32-0\)
\(x-5=-32\)
\(x=-32+5\)
\(x=-27\)
1)10-x=5-7
x=10-(-2)
x=12
2)x+5=0+32
x=32-5
x=27
3) -12+2x-9+x=0
-12+(2x+x-9)=0
3x-9=0+12
3x=12+9
x=21:3
x=7
4) 15-x=1-11
x=15-(-10)
x=25
5) 4-(27+3)=x-9
4-30=x-9
-26+9=x
x=-17
Tìm x, biết :
a, 2x - (-3x - 17) = 53 - 26 - x
b,5x - (-24) =33-78+4x
c,(7x - 19) - (5x -12) = 3x - (9-2x) -1
d,(2x +5)2 = -125
e,(4x - 3)2 = 289
f,-2*(12-5x)3 = -686
g,2mũ x+5 -3*2mũ x = 928
h,3mũ x +3 mũ x+1 + 3mũ x+2 = 13