\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(+x\times\frac{1}{8}\)\(=\frac{21}{24}\)

\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{21}{24}\)\(\div\frac{1}{8}\)

\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{168}{24}\)

\(x\times\frac{1}{2}\)\(=\)\(\frac{168}{24}\div\frac{1}{4}\)

\(x\times\frac{1}{2}\)\(=\frac{1344}{24}\)

\(x=\frac{1344}{24}\div\frac{1}{2}\)

\(x=112\)

đúng rồi đó

Bài 1: 

a: \(\dfrac{25}{42}-\dfrac{20}{63}=\dfrac{75-40}{126}=\dfrac{35}{126}=\dfrac{5}{18}\)

b: \(\dfrac{9}{20}-\dfrac{13}{75}-\dfrac{1}{6}=\dfrac{135}{300}-\dfrac{52}{300}-\dfrac{50}{300}=\dfrac{33}{300}=\dfrac{11}{100}\)

Nếu : 2 x X + 1 = 8 

Thì :  4 x X  + 1 = ?

Ta có:

2 x X + 1 = 8 

2 x X       =  8  -  1 

2 x X       =     7 

      X       =  7  :  2 

      X       =    3,5

Vậy X = 3,5 ...

Nên:  4  x   3,5  +  1 

    =       14  +   1 

    =    15 

... Vậy:  4 x X + 1 = 15

~ Hok T ~

1/\(\frac{\left(x+1\right)^2}{8}=\frac{8}{\left(x+1\right)^2}\)

=>\(\left(x+1\right)^4=8^2=64\)

=>\(x+1\in\left\{4;-4\right\}\)

=>\(x\in\left\{3;-5\right\}\)

2/ \(x+\frac{3}{4}=\frac{2}{5}\)

=>\(x=\frac{3}{4}-\frac{2}{5}=\frac{7}{20}\)

CHẳng hỉu j

Jmgoxpig och ogu o chxjf yvb

8vuob 

6 2/7  + 7 3/5 + 8 6/9 + 9 1/4 + 2/5 +  5/7 + 1/3  x 3/4 + 1967

= 44/7 + 38/5 + 78/9 + 37/4 + 2/5 + 5/7 + 1/3 + 1967

= ( 44/7 + 5/7 ) + ( 38/5 + 2/5 ) + ( 26/3 + 1/3 ) + ( 37/4 + 3/4 )  +1967

=  7 + 8 + 9 + 10  + 1967

= 15  + 9 + 10 + 1967

= 24 + 10 + 1967

= 34 + 1967 

= 2001

tính nhanh lớp 6 20 nhân 17-4 nhân 5 nhân 7

[x+1]+[x+2]+[x+3]+[x+4]+[x+5]=45

=[x+x+x+x+x]+[1+2+3+4+5]=45

=5x+15=45

5x=30

x=30:5

x=6

Vậy x=6

(x+1)+(x+2)+(x+3)+(x+4)+(x+5)=45

(x+x+x+x+x)+1+2+3+4+5=45

5x+15=45

5x=45-15

5x=30

x=30:5

x=6

vậy x=6