8,75 * x + 1,25 * x = 20

8,75 * x + 1,25 * x = 20

x                          = 20 : ( 8,75 + 1,25 )

x                          = 20 : 10

x                          = 2

=8.75+1.25)xX=2

10xX=2

X=2:10

X=0.2

đún thì cho mk nhé

chúc bạn học tốt

8,75 x X + 1,25 x X = 2

X x ( 8,75 + 1,25 ) = 2

X x 10 = 2

X = 2 : 10

X = 0,2

\(8,75.x+1,25.x=2\)

\(< =>x\left(8,75+1,25\right)=2\)

\(< =>x.10=2\)

\(< =>x=2:10=\frac{2}{10}=\frac{1}{5}\)

8,75 x X +1,25 x X = 280

X x [ 8,75 + 1,25 ] = 280

X x 10 = 280

X         =  280 / 10

X        = 28

giúp với đang gấp nha

sai rồi nguyen le bao nuyen tớ bấm nhầm thích đấy sai rồi 

sai từ cái đầu bai của cậu đấy

( 8,75 + 1,25 ) x X = 20 

10 x X = 20

       X = 20 : 10

      X = 2

cám mơn nhé 

8,75 x X + 1,25 x X = 20

= ( 8,75 + 1,25 ) x X = 20

=         10            x X = 20

X = 20 : 10 

X = 2

Thưn thịn thỳ t i c k cho Khả nha  

a) \(7,5.x:\left(8-\frac{118}{21}\right)=\frac{43}{15}\)

\(\frac{15}{2}.x:\frac{50}{21}=\frac{43}{15}\)

\(\frac{15}{2}.x.\frac{21}{50}=\frac{43}{15}\)

\(\frac{63}{20}.x=\frac{43}{15}\)

\(x=\frac{43}{15}:\frac{63}{20}\)

\(x=\frac{172}{189}\)

b) \(3.\left(x-\frac{1}{2}\right)-2.\left(x+1\right)=1,25.x-1\)

\(3x-\frac{3}{2}-2x-2=\frac{5}{4}.x-1\)

\(\Rightarrow3x-2x-\frac{5}{4}x=(-1)+\frac{3}{2}+2\)

\(x.\left(3-2-\frac{5}{4}\right)=\frac{5}{2}\)

\(x.\frac{\left(-1\right)}{4}=\frac{5}{2}\)

\(x=\frac{5}{2}:\left(\frac{-1}{4}\right)\)

\(x=-10\)

a: =>9x^2+6x+1-6(2x^2-13x+21)=0

=>9x^2+6x+1-12x^2+78x-126=0

=>-3x^2+84x-125=0

=>\(x\in\left\{26.42;1.58\right\}\)

b: =>(3x+1)[(2x-5)^2-(x-3)^2]=0

=>(3x+1)(2x-5-x+3)(2x-5+x-3)=0

=>(3x+1)(x-2)(3x-8)=0

=>\(x\in\left\{-\dfrac{1}{3};2;\dfrac{8}{3}\right\}\)

c; =>(x+5)(0,75x-3+1,25x)=0

=>(x+5)(2x-3)=0

=>x=3/2 hoặc x=-5

\(\Leftrightarrow x\left(-\dfrac{7}{2}-\dfrac{5}{4}\right)=\dfrac{1}{4}\cdot\dfrac{-4}{3}+\dfrac{1}{6}+\dfrac{3}{4}\)

\(\Leftrightarrow x\cdot\dfrac{-19}{4}=\dfrac{7}{12}\)

hay x=-7/57