Question

ДОПОМОЖІТЬ БУДЬ ЛАСКА!!!!!!!!!!!!!!!!!!! ТЕРМІНОВО!!!!!!!!!!!!!!!
ЗАВДАННЯ НА ФОТО
ДАЮ 50 БАЛІВ​

Answer 1

Пошаговое объяснение:

$1. \: 1) \: - 2 \times 15 = - 30 \\ 2) \: - 4 \times - 12 = 48 \\ 3) \: - 28 \div ( - 4) = 7 \\ 4) \: - 135 \div 27 = 5 \\ 5) \: 420 \div ( - 7) = - 60 \\ 6) \: {( - 4)}^{2} \div {( - 2)}^{3} = 16 \div ( - 8) = \\ = - 2$

$2. \: 2 {x}^{2} \times ( - 3 {y}^{3} ) = - 6 {x}^{2} {y}^{3} \\ x = - 1 \: \: \: \: \: y = - 2 \\ - 6 {x}^{2} {y}^{3} = - 6 \times {( - 1)}^{2} \times {( - 2)}^{3} = \\ = - 6 \times 1 \times ( - 8) = 48$

$3. \: 2(a + b) - 3(a - 2b) + a = 2a + 2b - 3a + 6b + a = 0a + 8b = 8b$

$4. \: 1) \: 2(x - 3) = - 8 \\ 2x - 6 = - 8 \\ 2x = - 8 + 6 \\ 2x = - 2 \\ x = \frac{ - 2}{2} \\ x = - 1$

$2) \: (x - 3)(x + 4) = 0 \\ {x}^{2} + 4x - 3x - 12 = 0 \\ {x}^{2} - x - 12 = 0 \\ d = ( - 1) ^{2} - 4 \times 1 \times ( - 12 )= \\ = 1 + 48 = 49 \\ x1 = \frac{ - ( - 1) + \sqrt{49} }{2 \times 1} = \frac{1 + 7}{2} = \frac{8}{2} = \\ = 4 \\ x2 = \frac{ - ( - 1) - \sqrt{49} }{2 \times 1} = \frac{1 - 7}{2} = \frac{ - 6}{2} = \\ = - 3$