a, (-x) = 2015^2015:2015^2015                  => (-x) =1   => x=-1

                                                   b, x = 27                                                             c, x = 2

                                                                           ^_^ Tick nhé ^_^

a, 2015²⁰¹⁵(-x)=2015²⁰¹⁵

=>2015²⁰¹⁵ :2015²⁰¹⁵=-x

=>1=-x

=>x=-1

Ta có : 148 : (x  + 2) = 378

=> x + 2 = 148 : 378

=> x + 2 = 74/189

=> x = 74/189 - 2 

=> x= -304/189 

a) x+2=148:378

x+2=74/189

x=-304/189

b)5.(x+8)=210

x+8=42

x=34

c)51+(26-3x)=275

26-3x=224

3x=-198

x=-66

1) 2x - 378 = 122

=> 2x = 122 + 378

=> 2x = 500

=> x = 500 : 2

=> x = 250

2) 8x - 4x = 1208

=> 4x = 1208

=> x = 1208 : 4

=> x = 302

3) x - 382 = 159 : 3

=> x - 382 = 53

=>  x = 53 + 382

=> x = 435

4) 3x + 30 = 420

=> 3x = 420 - 30

=> 3x = 390

=> x = 390 : 3

=> x = 130

5) 12x  - 13x - 500 = 1500

=> -x = 1500 + 500

=> -x = 2000

=> x = -2000

1,\(2x-378=122\)

\(2x=122+378\)

\(2x=500\)

\(x=500:2\)

\(x=250\)

2,\(8x-4x=1208\)

\(x.\left(8-4\right)=1208\)

\(x.4=1208\)

\(x=1208:4\)

\(x=302\)

3,\(x-382=159:3\)

\(x-382=53\)

\(x=52+382\)

\(x=434\)

4,\(3x+30=420\)

\(3x=420-30\)

\(3x=390\)

\(x=390:3\)

\(x=130\)

5,\(12x-13x-500=1500\)

như câu 2 

\(1,2x-378=122\)\(\Rightarrow2x=500\Rightarrow x=250\)

\(2,8x-4x=1208\)\(\Rightarrow4x=1208\Rightarrow x=302\)

\(3,x-382=159\div3\)\(\Rightarrow x-382=53\Rightarrow x=435\)

\(4,3x+30=402\)\(\Rightarrow3x=372\Rightarrow x=124\)

\(5,12x-13x-500=1500\)\(\Rightarrow-x-500=1500\Rightarrow-x=1000\Leftrightarrow x=-1000\)

a) Ta có: \(\dfrac{x^2+38x+4}{2x^2+17x+1}-\dfrac{3x^2-4x-2}{2x^2+17x+1}\)

\(=\dfrac{x^2+38x+4-3x^2+4x+2}{2x^2+17x+1}\)

\(=\dfrac{-2x^2+42x+6}{2x^2+17x+1}\)

c) Ta có: \(C=\dfrac{-x}{3x-2}+\dfrac{7x-4}{3x-2}\)

\(=\dfrac{-x+7x-4}{3x-2}\)

\(=\dfrac{6x-4}{3x-2}=2\)

   R(x) =           2x² + 3x - 1

^-  M(x) =   -x³ + x² 

                x³ + x² + 3x - 1

Vậy R(x) - M(x) = x³ + x² + 3x - 1

a) (3x + 1)^2 - 2(3x + 1)(3x - 5) + (3x - 5)^2 

= 9x^2 + 6x + 1 - 18x^2 + 24x + 10 + 9x^2 - 30x + 25

= 36

b) (3x^2 - y)^2

= 9x^4 - 6x^2y + y^2

c) (3x + 5)^2 + (3x - 5)^2 - (3x + 2)(3x - 2)

= 9x^2 + 30x + 25 + 9x^2 - 30x + 25 - 9x^2 + 4

= 9x^2 + 54

d) 2x(2x - 1)^2 - 3x(x + 3)(x - 3) - 4x(x + 1)^2

= 8x^3 - 8x^2 + 2x - 3x^2 + 27x - 4x^3 - 8x^2 - 4x

= x^3 - 16x^2 + 25x

e) (x - 2)(x^2 + 2x + 4) - (x + 1)^2 + 3(x - 1)(x + 1)

= x^3 - 8 - x^2 - 2x - 1 + 3x^2 - 2

= x^3 + 2x^2 - 2x - 12

f) (x^4 - 5x^2 + 25)(x^2 + 5) - (2 + x^2)^2 + 3(1 + x^2)^2

= x^6 + 125 - 4 - 4x^2 - x^2 + 3 + 6x^2 + 3x^4

= x^6 + 2x^4 + 2x^2 + 124

chiu roi 

ban oi $$

sao cung duoc nhe Vy Do

tk nhe@@@@@@@@@@__@

mình nghĩ để sai. biểu thức ở giữa phải là (3x-1)^2 mới đúng