( 4/9 + 7/9 -  2/9 ) x 19/24  = 1 x 19/24 = 19/24

\(=\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

\(\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)\)

\(=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

Đặt \(a=24-x,b=x-25\)

Khi đó pt ban đầu trở thành :

\(\frac{a^2+ab+b^2}{a^2-ab+b^2}=\frac{19}{49}\)

\(\Leftrightarrow49\left(a^2+ab+b^2\right)=19\left(a^2-ab+b^2\right)\)

\(\Leftrightarrow30a^2+68ab+30b^2=0\)

\(\Leftrightarrow15a^2+34ab+15b^2=0\)

\(\Leftrightarrow\left(3a+5b\right)\left(5a+3b\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}3a=-5b\\5a=-3b\end{cases}}\)

Đến đây bạn thay vào là dễ rồi nhé ! Chúc bạn học tốt !

a ) ( 165 + 99 + 165 x 1 ) - ( 163 x 101 - 163 x 1 ) 

= ( 165 x ( 99 + 1 ) ) - ( 163 x ( 101 - 1 ) )

= 165 x 100 - 163 x 100 

= 16500 - 16300

= 200

b ) 24 x 62 + 24 x 2 x 19

= 24 x 62 + 24 x 38

= 24 x ( 62 + 38 )

= 24 x 100

= 2400

= 

a) ( 165 x 99 + 165 x 1 ) - ( 163 x 101 - 163 x 1 )

= 165 x ( 99 + 1 )  -  163 x ( 101 - 1 )

= 165 x  100 - 163 x 100

= 100 x ( 165 - 163 )

= 100 x 2

= 200

b) 24 x 62 + 24 x 2 x 19

= 24 x 62 + 24  x 38

= 24 x ( 62 + 38 )

= 24 x 100

= 2400

( 165 x 99 + 165 x 1 ) - ( 163 x 101 - 163 x 1)

=[165 x ( 99 + 1 )] - [ 163 x ( 101 - 1)]

=165 x 100 - 163 x 100

= 100 x ( 165 - 163)

=100 x 2 = 200

24 x 62 + 24 x 2 x 19

= 24 x 62 + 24 x 38

= 24 x ( 62 + 38 )

=24 x 100 =2400

\(\frac{x-19}{24}\)+ \(\frac{x-19}{25}\)= \(\frac{x-19}{26}\)+ \(\frac{x-19}{27}\)

<=> \(\frac{x-19}{24}\)+ \(\frac{x-19}{25}\)- \(\frac{x-19}{26}\)- \(\frac{x-19}{27}\)= 0 

<=> \(\frac{x}{24}\)- \(\frac{19}{24}\)+ \(\frac{x}{25}\)- \(\frac{19}{25}\)- \(\frac{x}{26}\)+\(\frac{19}{26}\)- \(\frac{x}{27}\)+\(\frac{19}{27}\)= 0 

<=> \(\left(\frac{x}{24}+\frac{x}{25}-\frac{x}{26}-\frac{x}{27}\right)+\left(-\frac{19}{24}-\frac{19}{25}+\frac{19}{26}-\frac{19}{27}\right)=0\)

<=> \(x\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)-19\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)=0\)

<=> \(x\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)\)= \(19\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)\)

<=> x = 19

657892 chia 7896=

Câu 1 : 65.(-19)+19.(-24)= (-65).19+19.(-24)=19.[(-65)+(-24)]=19.(-89)=-1691                        
Câu 2:a) 7x.(2+x)-7x(x+3)=14                
            =>7x.(2+x-x-3)=14     
            =>7x.(-1)=14     
            =>(-7).x=14     
            =>x=14:(-7)    
            =>x=-2   
Vậy x=-2

= 0

0

0

Sửa đề : \(-\dfrac{19}{37}=\dfrac{19}{37}\)

\(\dfrac{19}{37}-\dfrac{31}{24}-\dfrac{19}{37}+1\dfrac{7}{24}-\dfrac{2}{13}\)

\(=\dfrac{19}{37}-\dfrac{31}{24}+\dfrac{19}{37}+\dfrac{31}{24}-\dfrac{2}{13}\)

\(=\left(\dfrac{19}{37}-\dfrac{19}{37}\right)+\left(-\dfrac{31}{24}+\dfrac{31}{24}\right)-\dfrac{2}{13}=-\dfrac{2}{13}\)

Sửa đề: \(\dfrac{19}{37}-\dfrac{31}{24}+\dfrac{-19}{37}+1\dfrac{7}{24}-\dfrac{2}{13}\)

Ta có: \(\dfrac{19}{37}-\dfrac{31}{24}+\dfrac{-19}{37}+1\dfrac{7}{24}-\dfrac{2}{13}\)

\(=\left(\dfrac{19}{37}+\dfrac{-19}{37}\right)+\left(\dfrac{-31}{24}+1+\dfrac{7}{24}\right)-\dfrac{2}{13}\)

\(=\dfrac{-2}{13}\)

\(\dfrac{19}{37}-\dfrac{31}{24}-\dfrac{-19}{37}+1\dfrac{7}{24}-\dfrac{2}{13}=\dfrac{19}{37}-\dfrac{31}{24}+\dfrac{19}{37}+\dfrac{31}{24}-\dfrac{2}{13}=\left(\dfrac{19}{37}+\dfrac{19}{37}\right)+\left(\dfrac{-31}{24}+\dfrac{31}{24}\right)-\dfrac{2}{13}=\dfrac{38}{31}+0-\dfrac{2}{13}=\dfrac{122}{403}\)

\(x=\left(\dfrac{21}{19}-\dfrac{5}{19}\right)-\dfrac{24}{38}=\dfrac{4}{19}\)

\(\dfrac{24}{38}+x=\dfrac{21}{19}-\dfrac{5}{19}\\ \Rightarrow\dfrac{12}{19}+x=\dfrac{16}{19}\\ \Rightarrow x=\dfrac{16}{19}-\dfrac{12}{19}\\ \Rightarrow x=\dfrac{4}{19}\)

24/38+x= 16/19

x= 16/19-24/28

x= 16/19-6/7

x= -2/133