Question

ПОМОГИТЕ ПОЖАЛУЙСТА СРОЧНО!

1) Раскрой скобки: (x+10)⋅(x+3)

2) Раскрой скобки (x+10)⋅(x+1)

3) Реши уравнение: 21t2−(7t−3)⋅(3t+1)=−2

Answer 1

$(x + 10)(x + 3) = {x}^{2} + 3x + 10x + 30 = x {}^{2} + 13x + 30$

$(x + 10)(x + 1) = {x}^{2} + x + 10x + 10 = {x}^{2} + 11x + 10$

$21t {}^{2} - (7t - 3)(3t + 1) = - 2 \\ 21t {}^{2} - (21 {t}^{2} + 7t - 9t - 3) = - 2 \\ 21t {}^{2} - 21 {t}^{2} - 7t + 9t + 3 = - 2 \\ 2t + 3 = - 2 \\ 2t = - 2 - 3 \\ 2t = - 5 \\ t = - 5 \div 2 \\ t = - 2.5$