n tia gốc O nha,sorry

Bạn viết rõ ra đc ko? Mik ko hiểu

\(\frac{x+3}{-4}=-\frac{9}{x+3}\)

\(\Leftrightarrow\left(x+3\right)\left(x+3\right)=-4\cdot\left(-9\right)\)

\(\Leftrightarrow\left(x+3\right)^2=36\)

\(\Leftrightarrow\orbr{\begin{cases}\left(x+3\right)^2=6^2\\\left(x+3\right)^2=\left(-6\right)^2\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x+3=6\\x+3=-6\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=-9\end{cases}}\)

Vậy ....

quy đồng

\(\left(x+3\right)^2=36\)

\(\left(x+3\right)^2-6^2=0\)

áp dụng định lí "  \(a^2-b^2=\left(a+b\right)\left(a-b\right)\) ta được

\(\left(x+3-6\right)\left(x+3+6\right)=0\)

\(x=3,x=-9\)

ab = 27 + ba
ab-ba = 27
10a + b-10b-a = 27
9 (a-b) = 27
a-b = 3
ab = 96, 85, 74, 63, 52, 41, 30

Ta có \(n^2+2⋮n-1\)

\(\Rightarrow n\left(n-1\right)+n+1⋮n-1\)

\(\Rightarrow n+1⋮n-1\)

\(\Rightarrow n-1+2⋮n-1\)

=> \(2⋮n-1\)

=> \(n-1\inƯ\left(2\right)\)

\(\Rightarrow n-1\in-2;-1;0;1;2\)

\(\Rightarrow n\in\) \(-1;0;1;2;3\)

7x - 21 -15 + 5x = 11x - 5

12x - 36 = 11x - 5

12x - 11x = - 5 + 36

x = 31

TA có 7(x-3)-5(3-x)=11x-5

<=> 7x-21-15+5x=11x-5

<=> 12x-36=11x-5

<=>12x-11x=36-5

<=>x=31

Vậy x=31

nhân chéo là đc:

3(x+2)=-4(x-5)

3x+6=-4x+20

3x+4x=20-6

7x     =14

 x      =2

Vậy x=2

1) x ( y + 1 ) = y + 6

=> xy + x     = y + 6

=> xy + x - y = 6

=> ( xy + x ) - y = 6

=> x ( y + 1 ) - ( y + 1 ) - 1 = 6

=> ( y + 1 ) . ( x - 1 ) = 7 = 7 . 1 = 1 . 7 = ( -1 ) . ( -7 ) = ( -7 ) . ( -1 )

Giải 4 trường hợp sẽ có x ; y cần tìm.

2) xy + 5x = y + 1

=> xy + 5x - y = 1

=> ( xy + 5x ) - y = 1

=> x ( y + 5 ) - ( y + 5 ) - 5 = 1

=> ( y + 5 ) . ( x - 1 ) = 6 = 1 . 6 = 6 . 1 = ( -1 ) . ( -6 ) = ( -6 ) .( -1 ) = 2 . 3 = 3 .2 = ( -2 ) . ( -3 ) = ( -3 ) . ( -2 ) 

Giải 8 trường hợp sẽ có x ; y cần tìm.

Chúc bn học tốt^^

Cảm ơn Cô nàng cự giải  nha

\(\frac{1+0,6-\frac{3}{7}}{\frac{8}{3}+\frac{8}{5}-\frac{8}{7}}=\frac{\frac{3}{3}+\frac{3}{5}-\frac{3}{7}}{\frac{8}{3}+\frac{8}{5}-\frac{8}{7}}=\frac{3.\left(\frac{1}{3}+\frac{1}{5}-\frac{1}{7}\right)}{8.\left(\frac{1}{3}+\frac{1}{5}-\frac{1}{7}\right)}=\frac{3.1}{8.1}=\frac{3}{8}\)

\(\frac{\frac{1}{3}+0,25-\frac{1}{5}+0,125}{\frac{7}{6}+\frac{7}{8}-0,7+\frac{7}{16}}=\frac{\frac{1}{3}+\frac{1}{4}-\frac{1}{5}+\frac{1}{8}}{\frac{7}{6}+\frac{7}{8}-\frac{7}{10}+\frac{7}{16}}=\frac{1.\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{5}+\frac{1}{8}\right)}{7.\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{5}+\frac{1}{8}\right)}=\frac{1.1}{7.1}=\frac{1}{7}\)

=>\(\frac{3}{8}-\frac{1}{7}=\frac{13}{56}\)

Mk đg cần gấp các bn giúp mk nha