x² - 25 + x ( x + 5 ) = 0

( x + 5 ) ( x - 5 ) + x ( x + 5 ) = 0 

( x + 5 ) ( x - 5 + x ) = 0

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

\(\left\{{}\begin{matrix}x+5=0\\2x-5=0\end{matrix}\right.\)

\(\left\{{}\begin{matrix}x=-5\\x=\dfrac{5}{2}\end{matrix}\right.\)

x= 5/2
x= -5

² - 25 + x ( x + 5 ) = 0

( x + 5 ) ( x - 5 ) + x ( x + 5 ) = 0 

( x + 5 ) ( x - 5 + x ) = 0

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

{x+5=02x−5=0{x+5=02x−5=0

\(\frac{x}{-4}=\frac{-25}{x}\)

\(\Rightarrow x^2=100\)

\(\Rightarrow x=\sqrt{100}\)

\(\Rightarrow x=10\)

x:(-4)=(-25):x

=> x=(-25):x.(-4)

=> x=100:x

=> \(x^2=100\)

=> x= 10 hoặc -10

tích đúng nha bn

Ta có : \(\frac{6}{11}x=\frac{9}{2}y\)=> \(\frac{12x}{22}=\frac{99y}{22}\)=> 12x = 99y => 4x = 33y => \(\frac{x}{33}=\frac{y}{4}\)

\(\frac{9}{2}y=\frac{15}{5}z\)=> \(\frac{45y}{10}=\frac{30z}{10}\)=> 45y = 30z => 3y = 2z => \(\frac{y}{2}=\frac{z}{3}\)

=> \(\frac{x}{33}=\frac{y}{4};\frac{y}{2}=\frac{z}{3}\)

=> \(\frac{x}{66}=\frac{y}{4};\frac{y}{4}=\frac{z}{12}\)

=> \(\frac{x}{66}=\frac{y}{4}=\frac{z}{12}\)và y - x + z = -120

Áp dụng t/c dãy tỉ số bằng nhau ta có :

\(\frac{x}{66}=\frac{y}{4}=\frac{z}{12}=\frac{y-x+z}{4-66+12}=\frac{-120}{-50}=\frac{12}{5}\)

=> \(\hept{\begin{cases}\frac{x}{66}=\frac{12}{5}\\\frac{y}{4}=\frac{12}{5}\\\frac{z}{12}=\frac{12}{5}\end{cases}}\)=> \(\hept{\begin{cases}x=\frac{792}{5}\\y=\frac{48}{5}\\z=\frac{144}{5}\end{cases}}\)

a ) 4.x - ( 2.x + 3 ) = x + 9 

     4.x - 2.x + 3      = x + 9

             2.x + 3      = x + 9

               x + 3       = 9

b ) 5.x - ( 2.x - 5 )  = 25 - x

     5.x - 2.x + 5      = 25 - 1.x

         3.x     + 5      = 25 - 1.x

         2.x     + 5      = 25

                   2.x      = 25 - 5

                   2.x      = 20

                      x      = 10

a)\(\frac{3}{5}+25-\frac{1}{5}=\frac{3}{5}-\frac{1}{5}+25=\frac{2}{5}+25=25\frac{2}{5}=\frac{129}{5}\)

b)\(6h45+14h30:5=6,75h+14,5h:5=6,75h+2,9h=9,65h\)

c)\(13.3.32,37+67,63.39=39.32,37+67,63.39=39.\left(32,37+67,63\right)=39.100=3900\)

d)

a.\(\frac{3}{5}+25-\frac{1}{5}=\left(\frac{3}{5}-\frac{1}{5}\right)+25=\frac{2}{5}+25=25.4\)

b. 6h45' + 14h30' : 5 = 6h45' + 2h54' = 9h 39'

c.13 x 3 x 32.5 + 67.63 x 39 = 3905.07

d.\(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{5}\right)\)

=\(\left(\frac{2}{2}-\frac{1}{2}\right)\cdot\left(\frac{3}{3}-\frac{1}{3}\right)\cdot\left(\frac{4}{4}-\frac{1}{4}\right)\)

=\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}=\frac{1}{4}\)

a) 3/5 + 25-1/5 = (3/5-1/5) + 25 = 2/5 +25 = 127/5
b) 6h45' + 14h30' : 5 = 6h45' + 2h54' = 9h39'
c) 13 x 3 x 32,37+ 67,63 x 39 = 39 x 32,37 + 67,63 x 39 = 39 x ( 32,37 + 67,63) = 39 x 100 = 3900
d) ( 1 - 1/2) x (1-1/3) x (1 - 1/4) x (1- 1/5) = (1/2 x 2/3) x (3/4 x 4/5) = 1/3 x 3/5 = 1/5

tìm x nha

+(x-3)²-x²=11

x²-6x+9-x²=11

-6x+9=11

-6x=2

x=2:-6

x=-1/3

(6x-3)²-36x(x-1)=40

36x²-36x+9-36x²+36x=40

9=40

=> đề sai

(2-x)²-7(x²+11)=0

4-4x+x²-7x²-77=0

-73-4x-6x²

ht bt 

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

=> x² + 7x + 10 - 12x + 9 = 25 - 10x + x² 

=> x² + 7x + 10 - 12x + 9 - 25 + 10x - x² = 0

=> 5x - 6 = 0 

=> x = 6/5

cần tớ giải giúp không

a)( x+ 2) ^3-( x-2)^3 = 12x(x-1) -8 
<=> (x+2-x+2)[( x+2)^2 + (x+2)(x-2) +(x-2)^2]= 12x^2 - 12x- 8 
<=> 4[ x^2 + 4x + 4 + x^2 - 4 + x^2 - 4x + 4] = 12x^2 - 12x- 8 
<=> 4( 3x^2 + 4) = 12x^2 - 12x- 8 
<=> 12x^2 + 16 = 12x^2 - 12x- 8 
<=> 12x= -24 
<=> x = -2 
Vậy x = -2.

b)

khó quá để em suy nghĩ một lúc nữa đã

\(2.x-15=11\)

            \(2x=11+15\)

            \(2x=26\)

              \(x=26:2\)

              \(x=13\)

\(b,4.\left(2-x\right)-5\left(3-x\right)=-12\)

             \(8-4x-15+5x=-12\)

                                     \(x-7=-12\)

                                             \(x=-12+7\)

                                             \(x=-5\)

\(c,\left|x-7\right|+13=25\)

               \(\left|x-7\right|=25-13\)

               \(\left|x-7\right|=12\)

\(\Rightarrow\orbr{\begin{cases}x-7=12\\x-7=-12\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=19\\x=-5\end{cases}}\)

a, 2.x - 15 = 11

           2.x = 11 + 15

           2.x = 26

              x = 26 : 2

              x = 13

b, 4.(2 - x) - 5(3 - x) = -12

        8 - 4x - 15 - 5x = -12

                     -7 + x = -12 

                            x = -12 + 7 

                            x = -5

c, |x - 7| + 13 = 25

            |x - 7|= 25 - 13

            |x - 7 | = 12

                   x = 12 + 7

                  x = 19