tìm x :
a) 3 x X x 3 = 3 ,45
b) 84 x X x 0,25 = 1,05
Tính:
4,32 : ( 0,73 + 1,67 ) + 3,16
125 x 0,01 + 0,25 : 0,01
Bài 2
a) Tính bằng cách thuận tiện:
23,45 : 12,5 : 0,8 705 : 45 – 336 : 45
b) Tìm X 0,4 x X = 0,6 x 5 X : 0,25 + X x 11 = 24
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,y,z :
a , 3/2x = 4/5y = 6/7z và x- y -2z= -45
b , x/2 = y/3 = z/4 và x^2 - y^2 + 2z^2=108
c, x^3 /8 = y^3/64 = z^3/216 và x^2 + y ^2 + z^2 = 14
b) Đặt \(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{4}=k\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=2k\\y=3k\\z=4k\end{matrix}\right.\)
Ta có: \(x^2-y^2+2z^2=108\)
\(\Leftrightarrow\left(2k\right)^2-\left(3k\right)^2+2\cdot\left(4k\right)^2=108\)
\(\Leftrightarrow4k^2-9k^2+2\cdot16k^2=108\)
\(\Leftrightarrow k^2=4\)
Trường hợp 1: k=2
\(\Leftrightarrow\left\{{}\begin{matrix}x=2k=2\cdot2=4\\y=3k=3\cdot2=6\\z=4k=4\cdot2=8\end{matrix}\right.\)
Trường hợp 2: k=-2
\(\Leftrightarrow\left\{{}\begin{matrix}x=2k=2\cdot\left(-2\right)=-4\\y=3k=3\cdot\left(-2\right)=-6\\z=4k=4\cdot\left(-2\right)=-8\end{matrix}\right.\)
tìm x biết:
a/ 3/2*x-70/10/11:(131313/151515+131313/353535+131313/999999)=-5
b/ 0,25*x*(8/5:1/1/2+1/50)=7/50*(2,91+0,09)*4
c/ (2/11*13+2/13*15+...+2/19*21) *462-(0,04:(x + 1,05)):0,12=19
Tìm x
a, x x 1,2 + x x 1,8 = 45
b, \(\dfrac{13+x}{20}=\dfrac{3}{4}\)
Các bạn ơi giúp mình với
b. \(\dfrac{13+x}{20}\)= \(\dfrac{15}{20}\)
=> 13+x=15
x=15-13
x=2
$#Shả$
`x xx1,2+x xx1,8=45`
`<=>x xx(1,2+1,8)=45`
`<=> x xx 3 =45`
`<=>x=45:3=15`
`(13+x)/20=3/4`
`<=>4xx(13+x)=20xx3`
`<=>4xx(13+x)=60`
`<=>13+x=60:4=15`
`<=>x=15-13=2`
a. x x(1,2+1,8)=45
x x 3= 45
x= 45:3
x=15
Tìm các số nguyên x, y; biết rằng:
a) x/-6=-15/45
b) x/5=16/25
c) 5/x-3=20/-12
d) 2/5.x=6/35
a) \(\dfrac{x}{-6}=\dfrac{-15}{45}\)
\(\dfrac{-x}{6}=\dfrac{-15}{45}\)
\(\dfrac{x}{6}=\dfrac{15}{45}\)
\(x=\dfrac{\left(15\cdot6\right)}{45}\)
\(x=2\)
b) \(\dfrac{x}{5}=\dfrac{16}{25}\)
\(x=\dfrac{\left(16\cdot5\right)}{25}\)
\(x=\dfrac{80}{25}\)
\(x=\dfrac{16}{5}\)
c) \(\dfrac{5}{x-3}=\dfrac{20}{-12}\)
\(x-3=\dfrac{\left(5\cdot-12\right)}{20}\)
\(x-3=-3\)
\(x=\left(-3\right)+3\)
\(x=0\)
d) \(\dfrac{2}{5}\cdot x=\dfrac{6}{35}\)
\(x=\dfrac{6}{35}\div\dfrac{2}{5}\)
\(x=\dfrac{3}{7}\)
Tìm x biết:
a , − x = 45 b , − x = − 45
a, x= 45 hoặc x= -45
b, Không có x nào thỏa mãn.
Bài 1: Tìm x, biết 4 – 2(x + 1) = 2
Bài 2. Tìm x biết: |2x – 3| - 1 = 2
Bài 3. Tìm x, biết: 3 1 3 x + 16 3 4 = - 13,25
Bài 4: Tìm x biết: 60% x + 2 3 x = - 76
Bài 5: Tìm x, biết: a) 11 - (-53 + x) = 97 b) -(x + 84) + 213 = -16
thanks
Bài 1:
Ta có: \(4-2\left(x+1\right)=2\)
\(\Leftrightarrow2\left(x+1\right)=2\)
\(\Leftrightarrow x+1=1\)
hay x=0
Bài 2:
Ta có: \(\left|2x-3\right|-1=2\)
\(\Leftrightarrow\left|2x-3\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)
Bài 3: Tìm x
a) X : 0,25 + X × 0,25 = 3,4 b) 0,7 : X + 0,5 : X = 0,75
x:0,25 + X x0,25=3,4
(0,25+0,25) :x=3,4
0,5:x=3,4
x=3,4:0,5
x=6,8
a) \(x:0,25+x.0,25=3,4\)
\(\Leftrightarrow x:\dfrac{1}{4}+\dfrac{1}{4}x=3,4\)
\(\Leftrightarrow4x+\dfrac{1}{4}x=3,4\Leftrightarrow\dfrac{17}{4}x=3,4\Leftrightarrow x=3,4:\dfrac{17}{4}\)
\(\Leftrightarrow x=0,8\)
b) \(0,7:x+0,5:x=0,75\)
<=> \(\left(0,7+0.5\right):x=0,75\)
<=> \(1,2:x=0,75\)
<=> \(x=1,6\)