Question

Решите уравнения:
а)x^2+6x+5=0
б)2x^2-5x+3=0
в)2x^2-7x-4=0

Answer 1

$x^2+6x+5=0\ D=36-20=16; sqrt{D} =4\ x_{1/2}= frac{-6pm4}{2}\\ x_1= -frac{10}{2}=-5\\ x_2=- frac{2}{2}=-1\\\ 2x^2-5x+3=0\ D=25-24=1; sqrt{D} =1\ x_{1/2}= frac{5pm1}{4}\\ x_1= frac{4}{4} =1\\ x_2= frac{6}{4} = frac{3}{2}\\\ 2x^2-7x-4=0\ D=49+32=81; sqrt{D}=9\ x_{1/2}= frac{7pm9}{4}\\ x_1=- frac{2}{4}=- frac{1}{2}\\ x_2= frac{16}{4}=4$

Answer 2

a) D=36-20=16=4²
x1=(-6+4)/2= -1
x2=(-6-4)/2= -5

b) D=25-24=1
x1=(5+1)/4=6/4=3/2=1.5
x2=(5-1)/4=1

v) D=49+32=81=9²
x1=(7+9)/4=4
x2=(7-9)/4= -2/4=-1/2= -0.5