tìm x biết
a) (7-x) - (25+7) = -25
b) x - [42 +(-28)] = -8
Tìm x biết
a)3.5x+1- 100 = - 25
b)4x-26+2x=28
\(a,3.5^{x+1}-100=-25\\ 3.5^{x+1}=-25+100\\ 3.5^{x+1}=75\\ 5^{x+1}=75:3\\ 5^{x+1}=25\\ 2^{x+1}=5^2\\ x+1=2\\ x=2-1\\ x=1\)
\(b,4x-26+2x=28\\ 4x+2x-26\\ 6x-26=28\\ 6x=28+26\\ 6x=54\\ x=54:6\\ x=9\)
Tìm x biết
a) x2 - 25=0
b) x (x + 7) + x + 7=0
a) x= + - 5
b) x\(\in\)\(\left\{-1;-7\right\}\)
a/ \(x^2-25=0\)
\(\Rightarrow\left(x+5\right)\left(x-5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+5=0\Rightarrow x=-5\\x-5=0\Rightarrow x=5\end{matrix}\right.\)
b/ \(x\left(x+7\right)+x+7=0\)
\(x\left(x+7\right)+\left(x+7\right)=0\)
\(\left(x+7\right)\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+7=0\Rightarrow x=-7\\x+1=0\Rightarrow x=-1\end{matrix}\right.\)
a) x^2 - 25 = 0 <=> (x + 5)(x - 5) = 0
<=> x = -5 hoặc x = 5
b) x(x + 7) + x + 7 = 0 <=> (x + 7)(x + 1) = 0
<=> x = -7 hoặc x = -1
Tìm x:
a) |x+2|=0
b) |x-5|=|-7|
c) |x-3|=7-(-2)
d) (7-x) - (25+7)=-25
e) x-[42+(-28)]=-8
f) |x-3|=|5|+|-7|
h) 9x-1=9
g)3×=9
h
e) x-[42+(-28)]=-8
=> x-14=-8
=> x=-8+14
=> x=-6
f) |x-3|=|5|+|-7|
=> |x-3|=5+7=12
=> x-3=12 hoặc x-3=-12
=> x=12+3 hoặc x=-12+3
=> =15 hoặc x=-9
h) 9x-1=9
=> 9x=9+1=10
=> x=10/9
g) 3x=9
=> x=9:3=3
( 7 - x ) - (25 +7) = - 25
x - [42 + ( -28 )] = - 8
|x - 3|= | 5 | + | - 7|
4 - (7 - x) =x - (13 - 4)
Các bn ơi !Giúp mk đi!
Ai nhanh mk k nhé !
\(\left(7-x\right)-\left(25+7\right)=-25\Leftrightarrow7-x-25-7=-25\)
\(\Rightarrow\left(7-7\right)-x-25=-25\Rightarrow-x=\left(-25\right)+25=0\Rightarrow x=0 \)
\(x-\left[42+\left(-28\right)\right]=-8\Rightarrow x-\left(42-28\right)=-8\)
\(\Rightarrow x-14=-8\Leftrightarrow x=\left(-8\right)+14=6\)
\(|x-3|=|5|+|-7|\Rightarrow|x-3|=5+7=12\)
\(\Rightarrow\hept{\begin{cases}x-3=12\\x-3=-12\end{cases}}\Rightarrow\hept{\begin{cases}x=12+3=15\\x=\left(-12\right)+3=-9\end{cases}}\)
\(4-\left(7-x\right)=x-\left(13-4\right)\Rightarrow4-7+x=x-13+4\)
\(\Rightarrow\left(-3\right)+x=x-9\Leftrightarrow2x=\left(-3\right)-9=-12\Rightarrow x=-6\)
Bài 1: Tìm x, biết
a) 3\(\dfrac{1}{3}\) x+ 16\(\dfrac{3}{4}\) = -13,25
b) 3\(\dfrac{2}{7}\).x - \(\dfrac{1}{8}\) = 2\(\dfrac{3}{4}\)
c) x : 4\(\dfrac{1}{3}\) = - 2,5
d) (\(\dfrac{3x}{7}\) + 1) : (-4) = \(\dfrac{-1}{28}\)
giúp em
`#040911`
`a)`
`3 1/3 x + 16 3/4 = -13,25`
`=> 3 1/3 x = -13,25 - 16 3/4`
`=> 3 1/3 x = -30`
`=> x = -30 \div 3 1/3`
`=> x =-9`
Vậy, `x = -9`
`b)`
`3 2/7*x - 1/8 = 2 3/4`
`=> 3 2/7x = 2 3/4 + 1/8`
`=> 3 2/7x = 23/8`
`=> x = 23/8 \div 3 2/7`
`=> x = 7/8`
Vậy, `x = 7/8`
`c)`
`x \div 4 1/3 = -2,5`
`=> x = -2,5 * 4 1/3`
`=> x = -65/6`
Vậy, `x = -65/6`
`d)`
`( (3x)/7 + 1) \div (-4) = (-1)/28`
`=> (3x)/7 +1 = (-1)/28 * (-4)`
`=> (3x)/7 + 1 = 1/7`
`=> (3x)/7 = 1/7 - 1`
`=> (3x)/7 = -6/7`
`=> 3x = -6`
`=> x = -6 \div 3`
`=> x = -2`
Vậy, `x = -2.`
a
=>10/3 . x + 16 + 3/4 = -13,25
=>10/3 x + 3/4 = -29,25
=>10/3 x = -30
=>x=-30 : 10/3
=>x=-30 . 3/10
=>x=-9
b.
=>23/7 x - 1/8 = = 11/4
=>23/7 x = 11/4 + 1/8
=>23/7 x= 22/8 + 1/8
=>23/7 x= 23/8
=>x=23/8 : 23/7
=>x=23/8 . 7/23
=>x=7/8
c.
=>x : 13/3 =-5/2
=>x=-5/2 . 13/3
=>x=-65/6
d.
=>3x/7 +1 = (-1/28) . (-4)
=>3x/7 + 1 = 1/7
=>3x/7 = -6/7
=>3x=-6
=>x=-2
a) \(3\dfrac{1}{3}x+16\dfrac{3}{4}=-13,25\)
\(\Rightarrow\dfrac{10}{3}x+\dfrac{67}{4}=-\dfrac{53}{4}\)
\(\Rightarrow\dfrac{10}{3}x=-30\)
\(\Rightarrow x=-30:\dfrac{10}{3}\)
\(\Rightarrow x=-9\)
b) \(3\dfrac{2}{7}x-\dfrac{1}{8}=2\dfrac{3}{4}\)
\(\Rightarrow\dfrac{23}{7}x-\dfrac{1}{8}=\dfrac{11}{4}\)
\(\Rightarrow\dfrac{23}{7}x=\dfrac{11}{4}+\dfrac{1}{8}\)
\(\Rightarrow\dfrac{23}{7}x=\dfrac{23}{8}\)
\(\Rightarrow x=\dfrac{23}{8}:\dfrac{23}{7}\)
\(\Rightarrow x=\dfrac{7}{8}\)
c) \(x:4\dfrac{1}{3}=-2,5\)
\(\Rightarrow x:\dfrac{13}{3}=-\dfrac{5}{2}\)
\(\Rightarrow x=-\dfrac{5}{2}\cdot\dfrac{13}{3}\)
\(\Rightarrow x=-\dfrac{65}{6}\)
d) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\Rightarrow\dfrac{3x}{7}+1=\dfrac{-1}{28}\cdot-4\)
\(\Rightarrow\dfrac{3x}{7}+1=\dfrac{1}{7}\)
\(\Rightarrow\dfrac{3x}{7}=-\dfrac{6}{7}\)
\(\Rightarrow x=-\dfrac{6}{7}:\dfrac{3}{7}\)
\(\Rightarrow x=-2\)
X-7 = -5 (x+2) = 0 (3x - 24) . 73 =2.74 | x - 5 | = |-7| x- [42 + ( -28) = -8 ( 7x - x ) - ( 25+7 ) = -25 |x-3| = |5| + | -7 | ( x : 3-4 ) : 5 =15 | x -3 | = 7 - (-2) 128 -3 . (x+4) = 23 4 - ( 7-x ) = x - (13-4 ) BÀI 2 : TÍNH NHANH S1 = 1+2+3+.......999 S1= 10 +12 + 14 +.......2010 S3 + 21 + 23 + 25 + .......10001
Tìm số nguyên x, biết :
a) x - 7 = -5
b) 128 - 3(x + 4) = 23
c) x - [42 + (-28)] = -8
d) (7 - x) - (25 + 7) = -25
Help me!!
c)x-[42+(-28)]=-8
x-34=-8
x =-8+34
x =26
a) x - 7 = -5
\(\Leftrightarrow x=-5+7=2\)
b) 128 - 3(x + 4) = 23
\(\Leftrightarrow128-3x-12=23\)
\(\Leftrightarrow-3x=23+12-128\)
\(\Leftrightarrow-3x=-93\)
\(\Leftrightarrow x=31\)
c) x - [42 + (-28)] = -8
\(\Leftrightarrow x-42+28=-8\)
\(\Leftrightarrow x=-8+42-28=6\)
d) (7 - x) - (25 + 7) = -25
\(\Leftrightarrow7-x-25-7=-25\)
\(\Leftrightarrow-x=-25+25+7-7\)
\(\Leftrightarrow x=0\)
a) x-7=-5
x=-5 + 7
x= 2
b)128-3(x+4)=23
3(x+4)=128-23
3(x+4)=105
x+4=105:3
x+4=35
x=35-4
x=31
c)x-42-(-28)=-8
x-42=-8+(-28)
x-42=-36
x=-36+42
x=6
d)(7-x)-(25+7)=-25
7-x-32=-25
7-x=-25+32
7-x=7
x=7-7
x=0
Tính giá trị của biểu thức:
42 + 24 : 8
71 – 13 x 4
28 x 3 : 7
139 – ( 45 + 25)
\(\dfrac{-2}{9}\)và\(\dfrac{6}{-27}\) b:\(\dfrac{-1}{-5}\)và\(\dfrac{4}{25}\)
Các cặp phân số sau có bằng nhau ko?vì sao?
Bài3: Tìm số nguyên X biết
a)\(\dfrac{-28}{35}\)=\(\dfrac{16}{x}\)
b)\(\dfrac{x+7}{15}\)=\(\dfrac{-24}{36}\)
giúp mình với ae cứu tôi ae cứu tôi :((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
Bài 2:
a: -2*(-27)=54
6*9=54
=>Hai phân số này bằng nhau
b: -1/-5=1/5=5/25<>4/25
Bài 3:
a: =>16/x=-4/5
=>x=-20
b: =>(x+7)/15=-2/3
=>x+7=-10
=>x=-17
a) \(\dfrac{-2}{9}\) và \(\dfrac{6}{-27}\)
\(\dfrac{6}{-27}=\dfrac{6:\left(-3\right)}{\left(-27\right):\left(-3\right)}=\dfrac{-2}{9}\)
Vậy \(\dfrac{-2}{9}=\dfrac{6}{-27}\)
b) \(\dfrac{-1}{-5}\) và \(\dfrac{4}{25}\)
\(\dfrac{-1}{-5}=\dfrac{\left(-1\right).\left(-5\right)}{\left(-5\right).\left(-5\right)}=\dfrac{5}{25}\)
Do \(5\ne4\Rightarrow\dfrac{5}{25}\ne\dfrac{4}{25}\)
Vậy \(\dfrac{-1}{-5}\ne\dfrac{4}{25}\)
Bài 3
a) \(\dfrac{-28}{35}=\dfrac{16}{x}\)
\(x=\dfrac{35.16}{-28}\)
\(x=-20\)
b) \(\dfrac{x+7}{15}=\dfrac{-24}{36}\)
\(\left(x+7\right).36=15.\left(-24\right)\)
\(36x+252=-360\)
\(36x=-360-252\)
\(36x=-612\)
\(x=\dfrac{-612}{36}\)
\(x=-17\)