Question

-438.' Розв'яжіть рiвняння: 1) (2x - 3) (4x + 3) - 8x² = 33; 2) (2x - 6) (8x + 5) + (3 - 4x) (3 + 4x) = 55; 3) 21x²-(3x-7)(7x-3)=37; 4) (x + 1) (x + 2) - (x - 3) (x + 4) = 12; 5) (-4x + 1) (x - 1) - x = (5 - 2x) (2x + 3) – 17.​

Answer 1

1)

$(2x - 3)(4x + 3) - 8 {x}^{2} = 33$

$8 {x}^{2} + 6x - 12x - 9 - 8 {x}^{2} = 33$

$- 6x - 9 = 33$

$- 6x = 33 + 9$

$- 6x = 42$

$x = 42\div ( - 6)$

$x = - 7$

2)

$(2x - 6)(8x + 5) + (3 - 4x)(3 + 4x) = 55$

$16 {x}^{2} + 10x - 48x - 30 + 9 + 12x - 12 x - 16 {x}^{2} = 55$

$-38x - 21 = 55$

$- 38x = 55 + 21$

$- 38x = 76$

$x = 76 \div ( - 38)$

$x = - 2$

3)

$21 {x}^{2} - (3x - 7)(7x - 3) = 37$

$21 {x}^{2} - 21 {x}^{2} + 9x + 49x - 21 = 37$

$58x - 21 = 37$

$58x = 37 + 21$

$58x = 58$

$x = 58 \div 58$

$x = 1$

4)

$(x + 1)(x + 2) - (x - 3)(x + 4) = 12$

${x}^{2} + 2x + x + 2 - {x}^{2} - 4x + 3x + 12 = 12$