Question

Tìm x, biết:
a, (2x + 1) - 4(x + 2)\(^2\) = 9
b, 3(x - 1)\(^2\) - 3x(x - 5) = 21
c, (x + 3)\(^2\) - (x - 4)(x + 8) = 1
d, 3(x + 2)\(^2\) + (2x - 1)\(^2\)- 7(x + 3)(x - 3) = 36
e, (x - 1)( x\(^2\)+ x + 1) - x(x + 2)(x - 2) = 5
f, (x - 1)\(^3\)- (x + 3)(x\(^2\)-3x + 9) + 3(x\(^2\) - 4) = 2

Answer 1

e, (x-1)(x² + x + 1)-x(x+2)(x-2) = 5

x(x² +x + 1 ) - (x² + x +1 )- [ x (x² - 4)] = 5

x³ +x² +x - x² - x - 1 - x³ +4x = 5

4x - 1 = 5

4x = 6

x =\(\dfrac{3}{2}\)

f, (x-1)³ - (x+3)(x² - 3x +9 ) +3(x² - 4) = 2

x - 3x² +3x - 1 - [( x³ - 3x² + 9x) + (3x² - 9x +27)] = 2

x³ - 3x² + 3x - 1 -x³ +3x² -9x - 3x² +9x - 27 +3x² - 12 = 2

3x - 1 - 27 - 12 = 2

3x = 42

x = 14

Answer 2

muốn tao trả lờ cho ko , mai đến lớp nhá

Answer 3

a, (2x+1)² - 4(x + 2)² = 9

4x² + 4x +1 -4(x² +4x + 4) = 9

4x² +4x + 1 - 4x² - 16x - 16 = 9

-12x - 15 = 9

-12x = 24

x = -2

b, 3(x-1)² - 3x(x-5) = 21

3(x² - 2x +1) - 3x² +15x = 21

3x² - 6x + 3 -3x² + 15x = 21

9x+3 = 21

9x = 18

x = 2

c,(x+3)² - (x-4)(x+8) = 1

x² + 6x + 9 - [x² + 8x - 4x - 32 ] = 1

x² + 6x + 9 - x² - 8x +4x +32 = 1

2x + 23 = 1

2x = -22

x = -11

d, 3(x + 2 )² + (2x- 1 )² - 7(x+3)(x-3) = 36

3(x² +4x + 4) + 4x² - 4x + 1 - 7(x² - 3²)= 36

3x² +12x +12 +4x² - 4x +1 - 7x² +63 = 36

8x +76 = 36

8x = -40

x = -5