Question

(x2 +12)/(x-3) = (7x)/(x-3) срочно через дискреминант ​

Answer 1

Ответ:

$x_1=4; x_2=3$

Объяснение:

$\frac{x^2+12}{x-3}=\frac{7x}{x-3}|*(x-3)\\x^2+12=7x\\x^2-7x+12=0\\D=49-4*12=1\\x_1=\frac{7+1}{2}=4\\x_2=\frac{7-1}{2}=3$

Answer 2

$( {x}^{2} + 12 )\times (x - 3) = 7x \times (x - 3) \\ {7x}^{2} - 21x = {x}^{3} - {3x}^{2} + 12x - 36 \\ {7x}^{2} - 21x - {x}^{3} + {3x}^{2} - 12x + 36 = 0 \\ - {x}^{3} + {10x}^{2} - 33x + 36 = 0 \\ { - x}^{3} + {3x}^{2} + {7x}^{2} - 21x - 12x + 36 = 0 \\ - (x - 3) \times ( {x}^{2} - 7x + 12) = 0 \\ - (x - 3) \times (x - 3)(x - 4) = 0 \\ {(x - 3)}^{2} \times (x - 4) = 0 \\ x1 = 3 \\ x2 = 4$