Вправи: 881

881. Solve only those equations that can be reduced to linear equations.

b) (x + 3)² – (x – 3)² = 12;

(x + 3 – (x – 3))(x + 3 + x – 3) = 12;

(x + 3 – x + 3) • 2x = 12;

6 • 2x = 12;

12x = 12;

x = 1.

c) (2x – 1)(4x² + 2x + 1) = x(3x – 2)(3x + 2) – x³;

4x³ + 4x² + 2x – 4x² – 2x – 1 = x(9x² – 4) – x³;

8x³ – 1 = 9x³ – 4x – x³;

8x³ – 9x³ + x³ + 4x = 1;

4x = 1| :4;

x = 0,25.

e) (3,7x – 2)(3,7x + 2) – (1,3x – 1)(1,3x + 1) = 6x(2x – 1);

13,69x² – 4 – (1,69x² – 1) = 12x² – 6x;

13,69x² – 4 – 1,69x² + 1 – 12x² + 6x = 0;

6x = 3|: 6;

x = 36;

x = 0,5.