a 180 -(x + 15) : 4 =80:5       180 - (x + 15) : 4 = 16       180 - ( x + 15) = 16 x 4         180 - ( x + 15 ) = 64       x + 15 = 180 - 64     x + 15 = 116     x= 116 - 15      x = 101

( x + 1 ) x số các số hạng : 2 = 1711

a) 180 - ( x + 15 ) : 4 x 5 = 80 

    180 - ( x + 15 ) = 80 x 4 

    180 - ( x + 15 ) = 320

    x + 15 = 320 - 180

    x + 15 = 140

    x = 140 - 15 

    x = 125 

14 : ( x - 17 ) = 2

(x-17) = 14 :2

x-17 = 7

x = 7+17

x = 24

14 : ( x - 17 ) = 2

         x - 17   = 14 : 2

         x - 17    = 7

          x          = 7 + 17

           x         = 24

Ta có : \(14:\left(x-17\right)=2\)

\(\Rightarrow x-7=14:2\)

\(\Rightarrow x-7=7\)

\(\Rightarrow x=14\)

\(\left(x-1\right)\left(x+1\right)-x\left(x+3\right)=0\)

\(\Rightarrow x^2-1-x^2-3x=0\Rightarrow-1=3x\Rightarrow x=-\dfrac{1}{3}\)

\(\left(x-1\right)\left(x+2\right)-x\left(x+3\right)=0\)

\(\Rightarrow x^2-1-x^2-3x=0\)

\(\Rightarrow3x=-1\Rightarrow x=-\dfrac{1}{3}\)

x²-1²  - x²- 3x=0 <=> -3x= 1 <=> x= -1/3

\(2\left(x-5\right)-17=25\)

\(2\left(x-5\right)=25+17\)

\(2\left(x-5\right)=42\)

\(x-5=42:2\)

\(x-5=21\)

\(x=21+5\)

\(x=26\)

Vậy x = 26

2(x - 5) - 17 = 25

2(x - 5) = 25 + 17

2(x - 5) = 42

x -  5 = 42 : 2 

x - 5 = 21

x = 21 
+ 5 = 26

2(x-5)-17=25

2(x-5)=25+17

2(x-5)=42

x-5=42:2

x-5=21

x=21+5

x=26

Vậy x=26

Nếu đề bài yêu cầu tính A, B thì chỉ cần thay giá trị của x vào rồi tính như bth là được nhé

a)Thay x=-13 vào biểu thức A=-(132-58)-x, ta đc:

          A=-(132-58)-(-13)

            =-74+13

            =-61

b)Thay x=43 vào biểu thức B=-(-213+57)-(213+x), ta đc:

           B=-(-213+57)-(213+43)

             =156-256

             =-100

a: =>x^2006-x=0

=>x(x^2005-1)=0

=>x=0 hoặc x=1

b: =>5^x*26=650

=>5^x=25

=>x=2

c: =>x(2y-1)-y+1/2=5/2

=>(y-1/2)(2x-1)=5/2

=>(2y-1)(2x-1)=5

=>\(\left(2x-1;2y-1\right)\in\left\{\left(1;5\right);\left(5;1\right);\left(-1;-5\right);\left(-5;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(1;3\right);\left(3;1\right);\left(0;-2\right);\left(-2;0\right)\right\}\)

\(a,\left(x+4\right)^2-x\left(x-5\right)=19\)

\(x^2+8x+16-x^2+5x=19\)

                               \(8x+5x=19-16\)

                                       \(13x=3\)

                                            \(x=\frac{3}{13}\)

\(b,x^2+3x-10=0\)

\(\Rightarrow x^2+5x-2x-10=0\)

\(\Rightarrow x\left(x+5\right)-2\left(x+5\right)=0\)

\(\Rightarrow\left(x-2\right)\left(x+5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-2=0\\x+5=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=-5\end{cases}}}\)

\(a,\left(x+4\right)^2-x\left(x-5\right)=19\)

\(x^2+8x+16-x^2+5x=19\)

                              \(8x+5x=19-16\)

                                      \(13x=3\)

                                           \(x=\frac{3}{13}\)

\(b,x^2+3x-10=0\)

\(\Rightarrow x^2+5x-2x-10=0\)

\(\Rightarrow x\left(x+5\right)-2\left(x+5\right)=0\)

\(\Rightarrow\left(x-2\right)\left(x+5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-2=0\\x+5=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=-5\end{cases}}}\)

a) (x+4)² - x(x-5) = 19

    x²+2.x.4+4² - x² +5x = 19

    8x +16 +5x =19

    13x +16 =19

     13x = 19-16=3

     => x=3:13=\(\frac{3}{13}\)

b) x² +3x -10 =0

    x(x+3) -10 =0

    x(x+3) =10

    => x=2

chúc bn học tốt nha ^^ t chi mk nhé <3

\(x^2\left(x-5\right)+5-x=0\\ \Rightarrow\left(x-5\right)\left(x^2-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=5\\x=-1\\x=1\end{matrix}\right.\)

\(\Leftrightarrow x^2\left(x-5\right)-\left(x-5\right)=0\)

\(\Leftrightarrow\left(x^2-1\right)\left(x-5\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(x-5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x+1=0\\x-5=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-1\\x=5\end{matrix}\right.\)

\(x^2\left(x-5\right)+5-x=x^2\left(x-5\right)-x+5=x^2\left(x-5\right)-\left(x-5\right)=\left(x-5\right)\left(x^2-1\right)\)