Question

1) 3x^2+5x-8=0 2) x^2+5x+10=0 3) 7x^2-14x+7=0 4) -x^2+3x+4=0 5) 4(x-1)^2-16x=0

Answer 1

1.
$3x^2+5x-8=0\\ D=25+96=121\\ x_1=(-5+11):6=1\\ x_2=(-5-11):6=- \frac{8}{3}$
2.
$x^2+5x+10=0\\ D=25-40=-15$
Т.к. D<0 решения нет
3.
$7x^2-14x+7=0\\ D=196-196=0\\ x=14:14=1$
4.
$-x^2+3x+4=0\\ x^2-3x-4=0\\ D=9+16=25\\ x_1=(3+5):2=4\\ x_2=(3-5):2=-1$
5.
$4(x-1)^2-16x=0 \\ x^2-2x+1-4x=0\\ x^2-6x+1=0\\ D=36-4=32\\ x_1=(6+4 \sqrt{2} ):2=3+2 \sqrt{2} \\ x_2=(6-4 \sqrt{2} ):2=3-2 \sqrt{2}$