Tìm x:
4/3x - x = 60%
Tìm x, biết :
a. 70 - 5. ( x - 3 ) = 45
b. 10 + 2.x = 45 : 43
c. 60 - 3 .x - 2 = 51
d. 4.x - 20 = 25 : 23
e. 2x.4 = 16
f. 3x.3 = 243
g. 64.4x = 168
h. 2x.162 = 1024
Tách ?
`a, 70 -5.(x-3) =45`
`=> 5.(x-3)= 70-45`
`=> 5.(x-3)=25`
`=>x-3=25:5`
`=>x-3=5`
`=>x= 5+3`
`=>x=8`
______
`b,10 + 2.x = 4^5:4^3`
`=> 10 + 2.x = 4^(5-3)`
`=> 10 + 2.x =4^2=16`
`=> 2.x=16-10`
`=>2.x=6`
`=>x=6:2`
`=>x=3`
_____
`c,60-3.x-2=51`
`=> 60-3.x= 51+2`
`=> 60-3.x=53`
`=>3.x=60-53`
`=> 3.x= 7`
`=>x= 7/3`
____
`d, 4.x-20=2^5:2^3`
`=> 4.x-20=2^(5-3)`
`=> 4.x-20=2^2`
`=> 4.x= 4+20`
`=>4.x=24`
`=>x=24:4`
`=>x=6`
____
`2^x . 4=16`
`=> 2^x=16:4`
`=>2^x= 4`
`=>2^x=2^2`
`=>x=2`
____
`f, 3^x . 3=243`
`=>3^x=243:3`
`=> 3^x=81`
`=> 3^x=3^3`
`=>x=3`
_____
`g, 64. 4^x =16^8`
`=> 4^3 . 4^x=(4^2)^8`
`=> 4^3 . 4^x = 4^(16)`
`=> 4^x= 4^(16-3)`
`=>4^x=4^(13)`
`=>x=13`
_____
`2^x . 16^2 =1024`
`=> 2^x= 1024 : 16^2`
`=>2^x=4`
`=>2^x=2^2`
`=>x=2`
a: =>5(x-3)=25
=>x-3=5
=>x=8
b: =>2x=16-10=6
=>x=3
c: =>58-3x=51
=>3x=7
=>x=7/3
d: =>4x-20=4
=>4x=24
=>x=6
e: =>2^x=4
=>2^x=2^2
=>x=2
f: =>3^x=81
=>3^x=3^4
=>x=4
g: =>4^x*4^3=4^16
=>x+3=16
=>x=13
h: =>2^x=1024/256=4=2^2
=>x=2
tìm x, biết
60%x +2/3x = 1368
Tìm x, biết:
a) (x-3)(x2+3x+9)+x(x+2)(2-x)=1
b) (x-2)3-(x-2)(x2+2x+4)+6(x-2)(x+2)=60
a) \(\left(x-3\right)\left(x^2+3x+9\right)+x\left(x+2\right)\left(2-x\right)=1\)
\(\Leftrightarrow x^3-27+x\left(4-x^2\right)=1\)
\(\Leftrightarrow x^3-27+4x-x^3=1\)
\(\Leftrightarrow4x-27=1\Leftrightarrow4x=28\Leftrightarrow x=7\)
b) \(\left(x-2\right)^3-\left(x-2\right)\left(x^2+2x+4\right)+6\left(x-2\right)\left(x+2\right)=60\)
\(\Leftrightarrow x^3-6x^2+12x+4-x^3-8+6\left(x^2-4\right)=60\)
\(\Leftrightarrow-6x^2+12x-4+6x^2-24=60\)
\(\Leftrightarrow12x-28=60\Leftrightarrow x=\frac{22}{3}\)
a) (x - 3)(x^2 + 3x + 9) + x(x + 2)(2 - x) = 1
x^3 + 3x^2 + 9x - 3x^2 - 9x - 27 + 2x^2 - x^3 + 4x - 2x^2 = 1
4x - 27 = 1
4x = 28
x = 7
b) (x - 2)^3 - (x - 2)(x^2 + 2x + 4) + 6(x - 2)(x + 2) = 60
x^3 - 4x^2 + 4x - 2x^2 + 8x - 8 - x(x^2 + 2x + 4) + 2(x^2 + 2x + 4) + 6x - 24 = 60
x^3 + 12x - 32 - x^2 - 2x^2 - 4x + 2x^2 + 4x + 8 = 60
12x - 24 = 60
12x = 60 + 24
12x = 84
x = 7
tìm x: (x^2+3x+2)(x^2+11x+30)-60 =0
\(\left(x^2+3x+2\right)\left(x^2+11x+30\right)-60=0\)
\(\Rightarrow\left[\left(x+1\right)\left(x+2\right)\right].\left[\left(x+5\right)\left(x+6\right)\right]-60=0\)
\(\Rightarrow\left[\left(x+1\right)\left(x+6\right)\right].\left[\left(x+2\right)\left(x+5\right)\right]-60=0\)
\(\Rightarrow\left(x^2+7x+6\right)\left(x^2+7x+10\right)-60=0\left(1\right)\)
Đặt \(x^2+7x+6=a\Rightarrow x^2+7x+10=a+4\)
Thay vào (1), ta có:
\(a\left(a+4\right)-60=0\)
\(\Rightarrow a^2+4a-60=0\)
\(\Rightarrow a^2+10a-6a-60=0\)
\(\Rightarrow a\left(a+10\right)-6\left(a+10\right)=0\)
\(\Rightarrow\left(a-6\right)\left(a+10\right)=0\)
\(\Rightarrow\orbr{\begin{cases}a=6\\a=-10\end{cases}}\)
- Nếu \(x^2+7x+6=6\)
\(\Rightarrow x^2+7x=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=-7\end{cases}}\)
- Nếu \(x^2+7x+6=-10\)
\(\Rightarrow x^2+7x+16=0\)
Mà \(x^2+7x+16=x^2+2.x.\frac{7}{2}+\frac{49}{4}+\frac{15}{4}=\left(x+\frac{7}{2}\right)^2+\frac{15}{4}>0\forall x\)
Vậy \(x=0,x=-7\)
Học tốt.
3x=4y=2z-x và x+y+z= 60 tìm x,y,z
Tìm x
1) -5(x + 1/5) - 1/2(x -2/3) = 3/2x - 5/6
2) 3(x - 1/2) - 5(x + 3/5) = -x + 1/5
3) 3(3x - 1/2)3 + 1/9 = 0
4) 60% .x + 2/3x =1/3 . 6/1/3
\(-5\left(x+\frac{1}{5}\right)-\frac{1}{2}\left(x-\frac{2}{3}\right)=\frac{3}{2}x-\frac{5}{6}\)
\(\Leftrightarrow-5x-\frac{1}{5}-\frac{1}{2}x+\frac{1}{3}=\frac{3}{2}x-\frac{5}{6}\)
\(\Leftrightarrow\left(-5x-\frac{1}{2}x\right)+\left(\frac{1}{3}-\frac{1}{5}\right)=\frac{3}{2}x-\frac{5}{6}\)
\(\Leftrightarrow\left(\frac{-10}{2}x-\frac{1}{2}x\right)+\left(\frac{5}{15}-\frac{3}{15}\right)=\frac{3}{2}x-\frac{5}{6}\)
\(\Leftrightarrow\frac{-11}{2}x+\frac{2}{15}=\frac{3}{2}x-\frac{5}{6}\)
\(\Leftrightarrow\frac{-11}{2}x-\frac{3}{2}x=-\frac{5}{6}-\frac{2}{15}\)
\(\Leftrightarrow\frac{-14}{2}x=-\frac{25}{30}-\frac{4}{30}\)
\(\Leftrightarrow-7x=-\frac{29}{30}\)
\(\Leftrightarrow x=-\frac{29}{30}\times\frac{-1}{7}\)
\(\Leftrightarrow x=\frac{29}{210}\)
\(3\left(x-\frac{1}{2}\right)-5\left(x+\frac{3}{5}\right)=-x+\frac{1}{5}\)
\(\Leftrightarrow3x-\frac{3}{2}-5x-3=\frac{1}{5}-x\)
\(\Leftrightarrow\left(3x-5x\right)-\left(\frac{3}{2}+3\right)=\frac{1}{5}-x\)
\(\Leftrightarrow-2x-\left(\frac{3}{2}+\frac{6}{2}\right)=\frac{1}{5}-x\)
\(\Leftrightarrow-2x-\frac{9}{2}=\frac{1}{5}-x\)
\(\Leftrightarrow-2x+x=\frac{1}{5}+\frac{9}{2}\)
\(\Leftrightarrow-x=\frac{2}{10}+\frac{45}{10}\)
\(\Leftrightarrow-x=\frac{47}{10}\)
\(\Leftrightarrow x=\frac{-47}{10}\)
\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)
\(\Leftrightarrow3\left(3x-\frac{1}{2}\right)^3=0-\frac{1}{9}\)
\(\Leftrightarrow3\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\div3\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{9}\times\frac{1}{3}\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\frac{-1}{27}\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\left(\frac{-1}{3}\right)^3\)
\(\Leftrightarrow3x-\frac{1}{2}=\frac{-1}{3}\)
\(\Leftrightarrow3x=\frac{-1}{3}+\frac{1}{2}\)
\(\Leftrightarrow3x=\frac{-2}{6}+\frac{3}{6}\)
\(\Leftrightarrow3x=\frac{1}{6}\)
\(\Leftrightarrow x=\frac{1}{6}\div3\)
\(\Leftrightarrow x=\frac{1}{6}\times\frac{1}{3}\)
\(\Leftrightarrow x=\frac{1}{18}\)
Tìm x: (3x+22).15=60
( 3x + 22 ).15 = 60
3x + 22 = 60 : 15
3x + 22 = 4
3x = 4 - 22
3x = -18
x = -18 : 3
x = -6
(3x+22).15=60
<=> 3x+22=4
<=> 3x=-18
<=> x=-6
(3x+22)x15=60
3x+22=60:15
3x+22=4
3x=4-22
3x=-18
x=-18:3
x=-6
Tìm x , y , z biết :
3x = 4y = 2z - x và x + y + z = 60
Ta có:\(3x=2z-x\Rightarrow4x=2z\Rightarrow2x=z\)
\(x+y+z=60\Rightarrow z=60-x-y\Rightarrow2x=60-x-y\Rightarrow3x=60-y\)
\(\Rightarrow4y=60-y\Rightarrow5y=60\Rightarrow y=12\)
\(\Rightarrow4y=3x=12.4=48\Rightarrow x=\frac{48}{3}=16\)
Mà \(2x=z\Rightarrow z=16.2=32\)
Vậy\(x=16;y=12;x=32\)
Ta có :
3x = 4y = 2z => \(\frac{x}{4}=\frac{y}{3}\)và \(\frac{y}{2}=\frac{z}{4}\)=> \(\frac{x}{8}=\frac{y}{6}\)và \(\frac{y}{6}=\frac{z}{12}\)
=> \(\frac{x}{8}=\frac{y}{6}=\frac{z}{12}\). Áp dụng tính chất dãy tỉ số bằng nhau, ta có :
\(\frac{x}{8}=\frac{y}{6}=\frac{z}{12}=\frac{x+y+z}{8+6+12}=\frac{60}{24}\)
Suy ra : \(\frac{x}{8}=\frac{60}{24}\Rightarrow x=\frac{60}{24}.8=20\)
\(\frac{y}{6}=\frac{60}{24}\Rightarrow y=\frac{60}{24}.6=15\)
\(\frac{z}{12}=\frac{60}{24}\Rightarrow x=\frac{60}{24}.12=30\)
Vậy : x = 20 ; y = 15 ; z = 20
Bạn ice ❅❅❅❅❅❅ dark sai rồi kết quả của bạn là x=20;y=15;x=30 không có tổng bằng 60
tìm số tự nhiên x biết :
a/ ( x + 4 ) -32 = 23
b/ 150 - 3x = 60
c/ 7x + 2x - 10 = 80
d/ 300 - 2( x-3 ) = 100
a)(x + 4) - 32 = 23
x + 4 = 23 + 32 = 55
x = 55 - 4 = 51
b) 150 - 3x = 60
3x = 150 - 60 = 90
x = 90 : 3 = 30
c) 7x + 2x - 10 = 80
9x = 80 + 10 = 90
x = 90 : 9 = 10
d) 300 - 2(x - 3) = 100
2x - 2 * 3 = 300 - 100 = 200
2x - 6 = 200
2x = 200 + 6 = 206
x = 206 : 2 = 103