Question

Решите уравнения; а)7x+3x=2x^2+3x+3 б)-7x^2=0 в)x^2-7x+10=0 г)2a^2-a=3 д)y^2-10y+25=0

Answer 1

$7x+3x=2x^2+3x+3$
$7x+3x-2x^2-3x-3=0$
$-2x^2+7x-3=0$
$(-1)(-2x^2+7x-3)=0$
$2x^2-7x+3=0$
$\sqrt{D} = \sqrt{b^2-4ac}$
$b=-7$
$a=2$
$c=3$
$\sqrt{D} = \sqrt{49-24} = \sqrt{25} =5$
$x_{1}= \frac{-b+ \sqrt{D} }{2a} = \frac{12}{4} =3$
$x_{2}= \frac{-b- \sqrt{D} }{2a} = \frac{1}{2}$

$-7x^2=0$ x=0
$x^2-7x+10=0$
x1=5 x2=2

a1=3 a2=-2

y1=-5