Tìm x biết :
a . (x + 3 ) : 5 + 15 = 60
b . ( 4 x - 1 ) . 3 = 27
c . x : 75 ; x : 90 và x < 10
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\(a,x-\dfrac{3}{4}=\dfrac{1}{7}\\ x=\dfrac{1}{7}+\dfrac{3}{4}\\ x=\dfrac{25}{28}\\ b,x+\dfrac{7}{5}=\dfrac{9}{8}.\dfrac{4}{27}\\ x+\dfrac{7}{5}=\dfrac{1}{6}\\ x=\dfrac{1}{6}-\dfrac{7}{5}\\ x=\dfrac{-37}{30}\\ c,\dfrac{2}{5}-\dfrac{3}{7}=\dfrac{x}{70}\\ \dfrac{-1}{35}=\dfrac{x}{70}\\ \dfrac{-2}{70}=\dfrac{x}{70}\\ x=-2\\ d,\dfrac{2}{9}-\dfrac{7}{8}.x=1\\ \dfrac{7}{8}.x=\dfrac{2}{9}-1\\ \dfrac{7}{8}.x=\dfrac{-7}{9}\\ x=\dfrac{-7}{9}:\dfrac{7}{8}\\ x=\dfrac{-8}{9}\)
\(a,x-\dfrac{3}{4}=\dfrac{1}{7}\)
\(\Rightarrow x=\dfrac{1}{7}+\dfrac{3}{4}\)
\(\Rightarrow x=\dfrac{25}{28}\)
\(b,x+\dfrac{7}{5}=\dfrac{9}{8}.\dfrac{4}{27}\)
\(\Rightarrow x+\dfrac{7}{5}=\dfrac{1}{6}\)
\(\Rightarrow x=\dfrac{1}{6}-\dfrac{7}{5}\)
\(\Rightarrow x=-\dfrac{37}{30}\)
\(c,\dfrac{2}{5}-\dfrac{3}{7}=\dfrac{x}{70}\)
\(\Rightarrow\dfrac{-1}{35}=\dfrac{x}{70}\)
\(\Rightarrow35x=-70\)
\(\Rightarrow x=-2\)
\(d,\dfrac{2}{9}-\dfrac{7}{8}.x=1\)
\(\Rightarrow\dfrac{7}{8}x=\dfrac{2}{9}-1\)
\(\Rightarrow\dfrac{7}{8}x=-\dfrac{7}{9}\)
\(\Rightarrow x=-\dfrac{8}{9}\)
a, x = -8 - 3 = -11
b, 35 + x = 27 + 12 = 39
=> x = 39 - 35 = 4
c, 2x = 31 - 15 = 16
=> x = 4
a) \(2^x=8\)
⇔ \(2^x=2^3\)
⇒ \(x=3\)
b) \(3^x=27\)
⇔ \(3^x=3^3\)
⇒ \(x=3\)
c) \(\left(-\dfrac{1}{2}\right)x=\left(-\dfrac{1}{2}\right)^4\)
⇔ \(x=\left(-\dfrac{1}{2}\right)^4\div\left(-\dfrac{1}{2}\right)\)
⇔ \(x=\left(-\dfrac{1}{2}\right)^3\)
d) \(x\div\left(-\dfrac{3}{4}\right)=\left(-\dfrac{3}{4}\right)^2\)
⇔ \(x=\left(-\dfrac{3}{4}\right)^2\cdot\left(-\dfrac{3}{4}\right)\)
⇔ \(x=\left(-\dfrac{3}{4}\right)^3=-\dfrac{27}{64}\)
d) \(\left(x+1\right)^3=-125\)
⇔ \(\left(x+1\right)^3=\left(-5\right)^3\)
⇔ \(x+1=-5\)
⇔ \(x=-5-1=-6\)
2:
a: (x-1,2)^2=4
=>x-1,2=2 hoặc x-1,2=-2
=>x=3,2(loại) hoặc x=-0,8(loại)
b: (x-1,5)^2=9
=>x-1,5=3 hoặc x-1,5=-3
=>x=-1,5(loại) hoặc x=4,5(loại)
c: (x-2)^3=64
=>(x-2)^3=4^3
=>x-2=4
=>x=6(nhận)
\(a,\Rightarrow\left(35x+3\right)\cdot19=152\\ \Rightarrow35x+3=8\\ \Rightarrow x=\dfrac{1}{7}\\ b,\Rightarrow3\left(x+7\right)=42\\ \Rightarrow x+7=14\Rightarrow x=7\\ c,\Rightarrow3\left(x+1\right)=48\\ \Rightarrow x+1=16\Rightarrow x=15\\ d,\Rightarrow120-5x+100\cdot2:5=4\cdot15\\ \Rightarrow120-5x+40=60\\ \Rightarrow5x=100\Rightarrow x=20\\ e,\Rightarrow4x-10=30\\ \Rightarrow4x=40\\ \Rightarrow x=10\\ g,\Rightarrow10x+10=70\\ \Rightarrow10x=60\\ \Rightarrow x=6\)
Tìm x biết
a) 350 - ( 3 . x ) : 75 = 170 - 69
350 - ( 3 . x ) : 75 = 101
( 3 . x ) : 75 = 350 - 101
( 3 . x ) : 75 = 249
3 . x = 249 . 75
3 . x = 18675
x = 18675 : 3
x = 6225
b) 3/4 + 1/4 : x = -3
1/4 : x = -3 - 3/4
1/4 : x = -15/4
x = 1/4 : -15/4
x = -1/15
c) 5,5x + 1 = 13/15
11/2x = 13/15 - 1
11/2x = -2/15
x = -2/15 : 11/2
x = -4/165
d) 3/7 - x = 1/4 - ( -3/5 )
3/7 - x = 1/4 +3/5
3/7 - x = 17/20
x = 3/7 - 17/20
x = -59/140
Tìm x biết :
a) 350 - ( 3 . x ) : 75 = 170 - 69
*Giải :
a) 350 - (3.x) : 75 = 170 -69
350 - ( 3.x) : 75 = 101
(3.x) : 75 = 350 - 101
( 3.x): 75 = 249
(3.x) = 249 .75
( 3. x ) = 18675
x = 18675 : 3
=> x = 6225
Vậy x = 6225 .
b) 3/4 + 1/4 : x = -3
*Giải :b) 3/4 + 1/4 : x = -3
1/4 : x = -3 -3/4
1/4 : x = -15/4
x =1/4 : ( -15/4 )
=> x = -1/15
Vậy x = -1/15 .
c)5,5x +1 = 13/15
*Giải : c) 5,5 x +1 = 13/15
11/2x = 13/15 -1
11/2x = -2/15
x = -2/15:11/2
=> x = -4/165
Vậy x = -4/165
d) 3/7 - x = 1/4 - ( -3/50)
*Giải : d) 3/7 - x = 1/4 - (-3/50)
3/7 - x = 1/4 + 3/5
3/7 - x = 17/20
x = 3/7 - 17/20
=> x = -59/140
Vậy x = -59/140
Chúc bn học tốt nha bạn
A. (X+3):5+15=60 CÒN CÂU B VÀ C TỚ LÀM SAU
(X+3):5 =60-15
(X+3):5 =45
X+3 =45:5
X+3 =7
X =7-3
X =4
Bạn làm luôn cho mình 2 câu cuối , mình đang cần câu B và câu C