x/-15=-60/x
-2/x=-x/8/25
3,8:(2x)=1/4:8/3
4/3:0,8=2/3:(0,1x)
a x;(-15)=-60:x
b -2:x=-x:8/25
c 4/3:0,8=2/3:(0,1x) nhờ các bạn nha
1. Tìm tỉ số \(\dfrac{x}{y}\) biết \(\dfrac{2x-y}{x+y}\)=\(\dfrac{2}{3}\)
2. Tìm x:
a) 3,8 : (2x) = \(\dfrac{1}{4}:2\dfrac{2}{3}\)
b) \(1\dfrac{1}{3}\) : 0,8 = \(\dfrac{2}{3}\) : (0,1x)
c) \(\dfrac{x}{-15}\) = \(\dfrac{-60}{x}\)
d) \(\dfrac{-2}{x}=\dfrac{-x}{\dfrac{8}{25}}\)
e) 0,2 : \(1\dfrac{1}{5}\)= \(\dfrac{2}{3}\) : (6x+7)
3. Tính A = \(\dfrac{8^{10}+4^{10}}{8^4+4^{11}}\)
bài 1) ta có : \(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow2\left(x+y\right)=3\left(2x-y\right)\)
\(\Leftrightarrow2x+2y=6x-3y\Leftrightarrow4x=5y\Leftrightarrow\dfrac{x}{y}=\dfrac{5}{4}\)
vậy \(\dfrac{x}{y}=\dfrac{5}{4}\)
bài 1
\(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow\dfrac{2.\dfrac{x}{y}-1}{\dfrac{x}{y}+1}=\dfrac{2.\dfrac{x}{y}+2-3}{\dfrac{x}{y}+1}=2-\dfrac{3}{\dfrac{x}{y}+1}=\dfrac{2}{3}\)
\(2-\dfrac{2}{3}=\dfrac{4}{3}=\dfrac{3}{\dfrac{x}{y}+1}\)
\(\left(\dfrac{x}{y}+1\right)=\dfrac{9}{4}\Rightarrow\dfrac{x}{y}=\dfrac{9}{4}-\dfrac{4}{4}=\dfrac{5}{4}\)
3) \(A=\dfrac{8^{10}+4^{10}}{8^4+4^{11}}=\dfrac{2^{30}+2^{20}}{2^{12}+2^{22}}\)
\(=\dfrac{2^{20}\left(2^{10}+1\right)}{2^{12}\left(2^{10}+1\right)}=\dfrac{2^{20}}{2^{12}}\)
\(=2^{20-12}=2^8\)
Vậy \(A=2^8\)
Tìm X trong các tỉ lệ thức sau:
a)3,8:(2X)=1/4:8/3
b)(0,25X):3=5/6:0,125
c)0,01:2,5=(0,75X):0,75
d)4/3:0,8=2/3:(0,1X)
Giữ lời hứa nka Nguyễn Mạnh Tân!
Hứa k r lm cko! Bài dài lắm
Tìm x trong các tỉ lệ thức sau:
a, 3,8 : ( 2x ) = 1/4 : 8/3
b, ( 0,25x ) : 3 = 5/6 : 0,125
c, 0,01 : 2,5 = ( 0,75x ) : 0,75
d, 4/3 : 0,8 = 2/3 : ( 0,1x )
( 0,25x ) : 3 = 5/6 : 0,125
( 1/4x ) : 3 = 5/6 : 1/8
( 1/4x ) : 3 = 5/6 x 8
( 1/4x ) : 3 = 20/3
1/4x = 20/3 x 3
1/4x = 20
x = 20 : 1/4
x = 80
0,01 : 2,5 = ( 0,75x ) : 0,75
1/100 : 25/10 = (3/4x) : 3/4
1/100 x 10/25 = (3/4x) : 3/4
=>(3/4x) : 3/4 = 1/250
3/4x = 1/250 x 3/4
3/4x = 3/1000
x = 3/1000 : 3/4
x = 1/250
4/3 : 0,8 = 2/3 : ( 0,1x )
<=>2/3 : (0,1x) = 4/3 : 0,8
2/3 : (0,1x) = 4/3 : 4/5
2/3 : (0,1x) = 4/3 x 5/4
2/3 : (0,1x) = 5/3
2/3 : (1/10x) = 5/3
1/10x = 2/3 : 5/3
1/10x = 2/3 x 3/5
1/10x = 2/5
x = 2/5 : 1/10
x = 2/5 x 10
x = 4
Tìm x, biết:
a) x + 15 = 34 : 3 + 8
b) 15 - (12 - x) = 22.
c) 4.(2x – 1) mũ 2 = 100
d) 2.3 mũ x – 16 = 146
Bài 3:cho
A=[0,8.7+(0,8)2].(1,25.7.4/5.1,25)+41,64
B=(1,09-0,29).4/5 phần (18,9-16,65)8/9
hỏi A gấp mấy lần B?
bài 4:tìm x thuộc Q biết:
a,-2/15-x-(-3/10)
b,3/4+1/4:x-2/5
b,2x.(x-1/4)-0
d,3/4.x-1/2-3/7
ai giúp mik vs
Bài 4:
b: Ta có: \(2x\left(x-\dfrac{1}{4}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{4}\end{matrix}\right.\)
BT 19 ( de bai - sbt- trang 7 tap 2 )
a) 1,2 - ( x - 0,8 ) = -2( 0,9+ x ) ;
b) 2,3x - 2(0,7 + 2x ) = 3,6 - 1,7x ;
c) 3(2,2 - 0,3x ) = 2,6 + (0,1x - 4 ) ;
d) 3,6 - 0,5(2x + 1) = x- 0,25(2-4x)
Giup mk vs m.n . thank m.n nha
a) 1,2 - ( x - 0,8 ) = -2( 0,9+ x )
<=> 1,2 - x + 0,8 = -1.8 - 2x
<=> x = -3,8
Vậy x = -3,8
b) 2,3x - 2(0,7 + 2x ) = 3,6 - 1,7x
<=> 2,3x - 1,4 - 4x = 3,6 - 1,7x
<=> -3,4x = 5
<=> x = \(\dfrac{-25}{17}\)
Vậy x = \(\dfrac{-25}{17}\)
c) 3(2,2 - 0,3x ) = 2,6 + (0,1x - 4 )
<=> 6,6 - 0,9x = 2,6 + 0,1x - 4
<=> -x = -8
<=> x = 8
Vậy x = 8
d) 3,6 - 0,5(2x + 1) = x- 0,25(2-4x)
<=> 3,6 - x - 0.5 = x - 0,5 + x
<=> -3x = -3,6
<=> x = 1.2
Vậy x = 1.2
-tìm x, biết:
a) -3/7+x=1/3
b) 3/4+1/4:x=2/5
c) 1/1/3 : 0,8=2/3:0,1x
d) |x-3|=1/2
a)\(-\frac{3}{7}+x=\frac{1}{3}\)
\(x=\frac{1}{3}+\frac{3}{7}\)
\(x=\frac{16}{21}\)
b)\(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
\(\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\)
\(\frac{1}{4}:x=-\frac{7}{20}\)
\(x=\frac{-7}{20}x\frac{1}{4}\)
\(x=-\frac{7}{80}\)
d)\(\left|x-3\right|=\frac{1}{2}\)
\(\Rightarrow\hept{\begin{cases}x-3=\frac{1}{2}\\x-3=\frac{-1}{2}\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{7}{2}\\x=\frac{5}{2}\end{cases}}\)
Mk bổ sung nha
c)\(1\frac{1}{3}:0,8=\frac{2}{3}:0,1x\)
\(\frac{5}{3}=\frac{2}{3}:0,1x\)
\(0,1x=\frac{2}{3}:\frac{5}{3}\)
\(0,1x=\frac{2}{5}\)
\(x=\frac{2}{5}:0,1\)
\(x=4\)
tim x :
a) ( x - 15 ) : 3 = 19
b) ( 5x - 45 ) x 15 = 450
c) 187 - 3( x + 4 ) = 34
d) 9x - 45 = 3^7 : 3^5
e ) ( 12x - 4^3 ) x 8^3 = 4 x 8^4
f ) x^2 = 4 , x^3 = 27
g ) ( x + 1 )^2 = 4
h ) ( 2x - 1 )^2 = 25
k ) ( 2x - 1 )^5 = 243
giup mik nhanh nhat co the nha
a) x = 72
b) x = 15
c) x = 34
d) x = 6
e)
f) x = 2 , x =3
g) x=1,x=-3
h)x=3,x=-2
mik chỉ bt giải thế thôi
CHÚC BẠN HỌC TỐT
Bài làm
a) ( x - 15 ) : 3 = 19
x - 15 = 19 . 3
x - 15 = 57
x = 57 + 15
x = 72
Vậy x = 72.
b) ( 5x - 45 ) . 15 = 450
5x - 45 = 450 : 15
5x - 45 = 30
5x = 75
x = 15
Vậy x = 15.
c) 187 - 3( x + 4 ) = 34
3( x + 4 ) = 187 - 34
3( x + 4 ) = 153
x + 4 = 153 : 3
x + 4 = 51
x = 47
Vậy x = 47.
d) 9x - 45 = 37 : 35
9x - 45 = 32
9x - 45 = 9
9( x - 5 ) = 9
x - 5 = 9 : 9
x - 5 = 1
x = 6
Vậy x = 6.
e ) ( 12x - 43 ) . 83 = 4 . 84
( 12x - 64 ) = 4 . 84 : 83
12x - 64 = 4 . 8
12x - 64 = 32
12x = 96
x = 8
Vậy x = 8.
f ) Đề bài không rõ ràng.
g ) ( x + 1 )2 = 4
=> ( x + 1 )2 = 22
=> x + 1 = 2
=> x = 1
Vậy x = 1.
h ) ( 2x - 1 )2 = 25
=> ( 2x - 1 )2 = 52
=> 2x - 1 = 5
=> 2x = 6
=> x = 3
Vậy x = 3
k ) ( 2x - 1 )5 = 243
=> ( 2x - 1 )5 = 35
=> 2x - 1 = 3
=> 2x = 4
=> x = 2
Vậy x = 2
# Học tốt #
a) ( x - 15 ) : 3 = 19
( x - 15 ) = 19 . 3
x - 15 = 57
x = 57 + 15
x = 72
b) ( 5x - 45 ) x 15 = 450
5x - 45 = 450 : 15
5x - 45 = 30
5x = 30 + 45
5x = 75
c) 187 - 3( x + 4 ) = 34
3( x + 4 ) = 187 - 34
3( x + 4 ) = 153
x + 4 = 153 : 3
x + 4 = 51
x = 51 - 4
x = 47
d) 9x - 45 = 37 : 35
9x - 45 = 32
9x - 45 = 9
9x = 9 + 45
9x = 54
x = 54 : 9
x = 6
e) ( 12x - 43 ) x 83 = 4 x 84
( 12x - 64 ) x 512 = 4 x 4096
( 12x - 64 ) x 512 = 16384
12x - 64 = 16384 : 512
12x - 64 = 32
12x = 32 + 64
12x = 96
x = 96 : 12
x = 8
f) x2 = 4
x2 = 22
=> x = 2
x3 = 27
x3 = 33
=> x = 3
g) ( x + 1 )2 = 4
( x + 1 )2 = 22
=> x + 1 = 2
x = 2 - 1
x = 1
h) ( 2x - 1 )2 = 25
( 2x - 1 )2 = 52
=> 2x - 1 = 5
2x = 5 + 1
2x = 6
x = 6 : 2
x = 3
k) ( 2x - 1 )5 = 243
( 2x - 1 )5 = 35
=> 2x - 1 = 3
2x = 3 + 1
2x = 4
x = 4 : 2
x = 2
Chúc bn hok tốt