tìm x
a,(x + 15):x = 4:3
b,(7,5 - x) : ( 3,5 + x) = 5 : 6
c,(x - 20) : (x - 10) = (x + 40) : (x + 70)
Tìm x, biết :
a) (x + 15) : x = 4:3
b) (7,5 - x) : (3,5 + x) = 5:6
c) (x - 20) : (x - 10) = (x + 40) : (x + 70)
\(a,\frac{x+15}{x}=\frac{4}{3}\Rightarrow4x=3x+45\Leftrightarrow x=45\)
\(b,\frac{7,5-x}{3,5+x}=\frac{5}{6}\Rightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Rightarrow x=2,5\)
\(c,\frac{x-20}{x-10}=\frac{x+40}{x+70}\Rightarrow\left(x-20\right)\left(x+70\right)=\left(x-10\right)\left(x+40\right)\)
\(\Leftrightarrow x^2+50x-1400=x^2+30x-400\)
\(\Leftrightarrow20x=1000\)
\(\Rightarrow x=50\)
Tìm x biết:
a, (x+15):x =4:3
b, (7,5-x) :(3,5+x)= 5:6
c, (x+20):(x-10)=(x+40):(x+70)
a. \(\frac{\left(x+15\right)}{x}=\frac{4}{3}\Leftrightarrow4x=3\left(x+15\right)\Leftrightarrow4x=3x+45\Leftrightarrow x=45\)
Vậy x=45
b. \(\frac{7,5-x}{3,5+x}=\frac{5}{6}\Leftrightarrow5\left(3,5+x\right)=6\left(7,5-x\right)\Leftrightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Leftrightarrow x=2,5\)
Vậy x=2,5
c. \(\frac{x+20}{x-10}=\frac{x+40}{x+70}\Leftrightarrow\left(x+40\right)\left(x-10\right)=\left(x+20\right)\left(x+70\right)\)
\(\Leftrightarrow x^2+30x-400=x^2+90x+1400\Leftrightarrow-60x=-30\Leftrightarrow x=-30\)
Vậy x=-30
a, (7,5-x):(3,5+x)=5:6
b, (x-20):(x-10)=(x+40):(x+70)
a, \(\left(7,5-x\right):\left(3,5+x\right)=5:6\)
\(\Leftrightarrow\frac{7,5-x}{3,5+x}=\frac{5}{6}\)
\(\Leftrightarrow6.\left(7,5-x\right)=5.\left(3,5+x\right)\)
\(\Leftrightarrow45-6x=17,5+5x\)
\(\Leftrightarrow45-17,5=5x+6x\)
\(\Leftrightarrow27,5=11x\)
\(\Leftrightarrow x=\frac{27,5}{11}=2,5\)
Vậy : \(x=2,5\)
b) Tương tự như câu a.
Chúc bạn học tốt nhé !!
Tìm x tỉ lệ thức
a, ( x + 15 ) : x = 4 : 3
b, ( 7,5 - x ) : ( 3,5 + x ) = 5 : 6
giúp mik vs
Tìm x, biết:
a) (x+15) : x = 4:3
b) (x-20) : (x-10) = (x+40) : (x+70)
a) (x + 15) : x = 4 : 3
=> x : x + 15 : x = \(\frac{4}{3}\)
=> 1 + 15 : x = \(\frac{4}{3}\)
=> 15 : x = \(\frac{4}{3}\)- 1 = \(\frac{1}{3}\)
=> x = 15 : \(\frac{1}{3}\)
=> x = 45
phượng quyên là otaku sa( hình đại diện so cute)
Tìm x biết
1) \(\frac{x+15}{x}\)= \(\frac{4}{3}\)
2) \(\frac{7,5-x}{3,5+x}\)= \(\frac{x+40}{x+70}\)
\(\frac{x+15}{x}=\frac{4}{3}\)
\(\Rightarrow3\left(x+15\right)=4x\)
\(3x+45=4x\)
\(4x-3x=45\)
\(x=45\)
\(\frac{7,5-x}{3,5+x}=\frac{x+40}{x+70}\)
\(\Rightarrow\left(7,5-x\right)\left(x+70\right)=\left(3,5+x\right)\left(x+40\right)\)
\(7,5x+525-x^2-70x=3,5x+140+x^2+40x\)
\(4x+385-2x^2=110x\)
\(385-2x^2=106x\)
Đề sai òi bạn ~ nếu cái đề này thì x = 412372022 ...... số vô tỉ =.= bậc lên cũng cũng không được số hữa tỉ nào auto ...
a |x-2| = 3
b 5|x+4| =15
c 70-|x+6| =20
d 20+|x+2| =40
júp mình với nha
Tìm x, biết :
\(a.3\dfrac{4}{5}:40\dfrac{8}{15}=0,25:x\)
\(b.\left(x+1\right):\dfrac{5}{6}=20:3\)
\(c.\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
a: Ta có: \(\dfrac{1}{4}:x=3\dfrac{4}{5}:40\dfrac{8}{15}\)
\(\Leftrightarrow x=\dfrac{1}{4}\cdot\dfrac{\dfrac{608}{15}}{3+\dfrac{4}{5}}\)
\(\Leftrightarrow x=\dfrac{152}{15}:\dfrac{19}{5}=\dfrac{8}{3}\)
b: Ta có: \(\left(x+1\right):\dfrac{5}{6}=\dfrac{20}{3}\)
\(\Leftrightarrow x+1=\dfrac{50}{9}\)
hay \(x=\dfrac{41}{9}\)
c: Ta có: \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
\(\Leftrightarrow x^2-1=63\)
\(\Leftrightarrow x^2=64\)
hay \(x\in\left\{8;-8\right\}\)
c. \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
\(7.9=\left(x-1\right).\left(x+1\right)\)
\(63=x^2-1\)
\(x^2=63+1\)
\(x^2=64\)
\(x^2=8^2\)
\(x=8\)
Tìm x, biết:
a) x-20 =-2x +37
b)4(x-5)-31=(-6)-(x+1)
c)-8(x+3)-x=10-(2x-5)
d)15-4(x+7)=-6+(x-10)