Question

Помогите пожалуйста с квадратными уравнениями (даю 30 баллов)

Answer 1

#1.

$3x^2 + 6x = 0\3x(x + 2) = 0\3x = 0; x+2 = 0\x = 0; x = -2$

#2.

$-2x^2 + 8x = 0\-2x(x - 4) = 0\\left[begin{array}{cc}-2x = 0\x - 4 = 0end{array}right\\left[begin{array}{cc}x = 0\x = 4end{array}right$

#3.

$x^2 - 4x = 0\x (x - 4) = 0\\left[begin{array}{cc}x = 0\x - 4 = 0end{array}right\\left[begin{array}{cc}x = 0\x = 4end{array}right$

#4.

$7x^2 - 14x = 0\7x(x - 2) = 0\\left[begin{array}{cc}7x = 0\x - 2 = 0end{array}right\\left[begin{array}{cc}x = 0\x = 2end{array}right$

#5.

$8x^2 + 3x = 0\x(8x + 3) = 0\\left[begin{array}{cc}x = 0\8x +3 = 0end{array}right\\left[begin{array}{cc}x = 0\8x = -3end{array}right\\left[begin{array}{cc}x = 0\x = frac{-3}{8} end{array}right$

#6.

$-x^2 + 8x = 0\-x(x - 8) = 0\left[begin{array}{cc}-x = 0\x -8 = 0end{array}right\\left[begin{array}{cc}x = 0\x = 8end{array}right$

#7.

a)

$x^2 + 1 = 82\x^2 = 82 - 1\x^2 = 81\\left[begin{array}{cc}x = 9\x = -9end{array}right$

б)

$5x^2 = 20\x^2 = 20 : 5\x^2 = 4\\left[begin{array}{cc}x = 2\x = -2end{array}right$

в)

$x^2 - 0,5x = 0\x (x - 0,5) = 0\\left[begin{array}{cc}x = 0\x -0,5 = 0end{array}right\\left[begin{array}{cc}x = 0\x = 0,5end{array}right$