Question

Помогите плиас. Алгебра 8 класс. Даю 25 баллов
1) 5x^2-10=0
2) 3x^2 + 4x = 0
3) x^2 + 6x - 7 = 0
4) x^2 - 3x+ 1 = 0
5) x^2 - x +3 = 0
6) 3x^2 + 7x + 2 = 0

Answer 1

$5 {x}^{2} - 10 = 0 \ {x}^{2} - 2 = 0 \ {x}^{2} = 2 \ x = sqrt{2} \ x = - sqrt{2}$

$3 {x}^{2} + 4x = 0 \ x(3x + 4) = 0 \ x = 0 \ 3x + 4 = 0 \ x = 0 \ x = - frac{4 }{3}$

${x}^{2} + 6x - 7 = 0 \ {x}^{2} + 7x - x - 7 = 0 \ x(x + 7) - (x + 7) = 0 \ (x + 7)(x - 1) = 0 \ x + 7 = 0 \ x - 1 = 0 \ x = - x = 1$

${x}^{2} - 3x + 1 = 0 \ x = frac{ - ( - 3) - + sqrt{( - 3 {)}^{2 } - 4 times 1 times 1} }{2 times1 } \ x = frac{3 + - sqrt{9 - 4} }{2} \ x = frac{ + - 3 sqrt{5} }{2} \ x = frac{{3 + sqrt{5} } }{2} \ x = - frac{ sqrt{3} - sqrt{5} }{2}$

$3 {x}^{2} + 7x + 2 = 0 \ 3 {x}^{2} + 6x + x + 2 = 0 \ 3x(x + 2) + x + 2 = 0 \ (x + 2)(3x + 1) = 0 \ x + 2 = 0 \ 3x + 1 = 0 \ x = - 1 \ x = - frac{ 1 }{3}$