Question

помогите решить уравнение за 9 класс
1. 7x2=(2x+1)2+3x2-5
2. (x-2)3+(x+2)3=2x(x2-1)+3
3. (x+3)(x-2)-(x-3)(x+2)-5=6x-7

Answer 1

1) 7x² = (2x + 1)² + 3x² - 5

7x² = 4x² + 4x + 1 + 3x² - 5

7x² - 4x² - 4x - 3x² = - 4

- 4x = - 4

x = 1

2) (x - 2)³ + (x + 2)³ = 2x(x² - 1) + 3

x³ - 6x² + 12x - 8 + x³ + 6x² + 12x + 8 = 2x³ - 2x + 3

2x³ + 24x = 2x³ - 2x + 3

2x³ + 24x - 2x³ + 2x = 3

26x = 3

x = 3/26

3) (x + 3)(x - 2) - (x - 3)(x + 2) - 5 = 6x - 7

x² - 2x + 3x - 6 - x² - 2x + 3x + 6 - 5 = 6x - 7

2x - 5 = 6x - 7

2x - 6x = - 7 + 5

- 4x = - 2

x = 0,5