a) 1245 - 3x = 735

3x = 1245 - 735

3x = 510

x = 510 : 3

x = 170

b) 14x - 8x + 34 = 94

6x + 34 = 94

6x = 94 - 34

6x = 60

x = 60 : 6

x = 10

c) 3^x+2 + 3^x = 270

3^x . 3² + 3^x . 1 = 270

3^x . ( 3² + 1 ) = 270

3^x . 10 = 270

3^x = 270 : 10

3^x = 27

3^x = 3³

=> x = 3

a)

3x=1245-735

3x=510

x  =510:3

x  =170

b)

6x+34=94

6x      = 94-34

6x      =60

x         =60:6

x         =10

c)

3^x.3²+3^x=270

3^x.(3²+1)=270

3^x.(9+1)=270

3^x.10      =270

3^x           =270:10

3^x            =27

3^x            =3³

 ^x             =3

1245-3x=735

3x=510

x=170

14x-8x+34=94

6x=60

x=10

giờ mình bận roi xin loi ban 

14x - 8x + 34  = 95

 x( 14 - 8)        = 95 - 34

  x .6              = 61

 x                   = 61/6 

a) 1245 - 3x = 735

               3x = 1245 - 735  

               3x = 510

                x = 510 : 3

                x = 170

b,14x - 8x + 34 = 94

        14x - 8x   =94-34

         14x - 8x  =60

        x(14-8)     = 60

              x.6    =60

                x     =60 :6

                x     =10

Bài này giải ra như thế này ! 

a ) 1245 -3x = 735 

=> 3x = 1245 - 735 = 510

=> x = 510 : 3 = 170 

b ) 14x - 8 x + 34 = 94

=> 6x = 94 -34 = 60

=> x = 60 : 6 = 10

a: ĐKXD: x<>0

\(\dfrac{14x^3+12x^2-14x}{2x}=\left(x+2\right)\left(3x-4\right)\)

=>\(\dfrac{2x\left(7x^2+6x-7\right)}{2x}=\left(x+2\right)\left(3x-4\right)\)

=>\(7x^2+6x-7=3x^2-4x+6x-8\)

=>\(7x^2+6x-7=3x^2+2x-8\)

=>\(4x^2+4x+1=0\)

=>\(\left(2x+1\right)^2=0\)

=>2x+1=0

=>x=-1/2(nhận)

b: \(\left(4x-5\right)\left(6x+1\right)-\left(8x+3\right)\left(3x-4\right)=15\)

=>\(24x^2+4x-30x-5-\left(24x^2-32x+9x-12\right)=15\)

=>\(24x^2-26x-5-24x^2+23x+12=15\)

=>-3x+7=15

=>-3x=8

=>\(x=-\dfrac{8}{3}\)

Bài 1.

a)

\((x-2)(2x-1)-(2x-3)(x-1)-2\\=2x^2-x-4x+2-(2x^2-2x-3x+3)-2\\=2x^2-5x+2-(2x^2-5x+3)-2\\=2x^2-5x+2-2x^2+5x-3-2\\=(2x^2-2x^2)+(-5x+5x)+(2-3-2)\\=-3\)

b)

\(x(x+3y+1)-2y(x-1)-(y+x+1)x\\=x^2+3xy+x-2xy+2y-xy-x^2-x\\=(x^2-x^2)+(3xy-2xy-xy)+(x-x)+2y\\=2y\)

Bài 2.

a)

\((14x^3+12x^2-14x):2x=(x+2)(3x-4)\\\Leftrightarrow 14x^3:2x+12x^2:2x-14x:2x=3x^2-4x+6x-8\\ \Leftrightarrow 7x^2+6x-7=3x^2+2x-8\\\Leftrightarrow (7x^2-3x^2)+(6x-2x)+(-7+8)=0\\\Leftrightarrow 4x^2+4x+1=0\\\Leftrightarrow (2x)^2+2\cdot 2x\cdot 1+1^2=0\\\Leftrightarrow (2x+1)^2=0\\\Leftrightarrow 2x+1=0\\\Leftrightarrow 2x=-1\\\Leftrightarrow x=\frac{-1}2\)

b)

\((4x-5)(6x+1)-(8x+3)(3x-4)=15\\\Leftrightarrow 24x^2+4x-30x-5-(24x^2-32x+9x-12)=15\\\Leftrightarrow 24x^2-26x-5-(24x^2-23x-12)=15\\\Leftrightarrow 24x^2-26x-5-24x^2+23x+12=15\\\Leftrightarrow -3x+7=15\\\Leftrightarrow -3x=8\\\Leftrightarrow x=\frac{-8}3\\Toru\)

Bài 1:

\(f\left(x\right)=x^2+8x+25\)

Cho \(f\left(x\right)=0\Rightarrow x^2+8x+25=0\)

\(\Rightarrow x^2+8x+16+9=0\)

\(\Rightarrow\left(x+4\right)^2+9=0\)

Dễ thấy: \(\left(x+4\right)^2\ge0\forall x\)

\(\Rightarrow\left(x+4\right)^2+9\ge9>0\forall x\) ( vô nghiệm )

Vậy đa thức \(f\left(x\right)=x^2+8x+25\) không có nghiệm

Bài 2:

\(f\left(x\right)=x^{14}-14x^{13}+14x^{12}-...+14x^2-14x+14\)

\(f\left(x\right)=x^{14}-\left(13+1\right)x^{13}+\left(13+1\right)x^{12}-...+\left(13+1\right)x^2-\left(13+1\right)x+\left(13+1\right)\)

Do \(f\left(x\right)=13\) nên ta chỗ nào có \(13\) ta thay bằng \(x\)

\(f\left(13\right)=x^{14}-\left(x+1\right)x^{13}+\left(x+1\right)x^{12}-...+\left(x+1\right)x^2-\left(x+1\right)x+\left(x+1\right)\)

\(f\left(13\right)=x^{14}-x^{14}-x^3+x^{13}+x^{12}-...+x^3+x^2-x^2-x+x+1=1\)

Vậy \(f\left(13\right)=1\)

a) 6x - 35 + 5x - 21 = (6x + 5x) - (35 + 21) = 11x - 56 = 17x - 20 => 11x = 17x - 20 + 56 = 17x + 36

=> 36 = 11x - 17x = -6x => x = 36 : (-6) = -6

b) 5x + 35 - 4x - 27 = (5x - 4x) + (35 - 27) = x + 8 = 14x + 34 => x = 14x + 34 - 8 = 14x + 26

=> 26 = x - 14x = -13x => x = 26 : (-13) = -2

(6x+5x)+(-35-21)=17x-20

11x-56=17x-20

11x-17x=-20+56

-6x=36

x=36/-6

x=-6

vậy x=-6

a) \(6x-35+5x-21=17x-20\)

\(\Rightarrow6x-25+5x-21+20=17x\)

\(\left(6x+5x\right)+\left(20-25-21\right)=17x\)

\(11x+\left(-36\right)=17x\)

\(17x-11x=-36\)

\(6x=-36\)

\(x=\frac{-36}{6}=-6\)

Vậy \(x=-6\)

b) \(5x+35-4x-27=14x+34\)

\(\Rightarrow5x+35-4x-27-34=14x\)

\(\left(5x-4x\right)+\left(35-27-34\right)=14x\)

\(x+\left(-26\right)=14x\)

\(14x-x=-26\)

\(13x=-26\)

\(x=-\frac{26}{13}=-2\)

Vậy \(x=-2\)