Răspuns:
[tex]2*x^{2} -8x+7=0\\[/tex]
Δ=[tex]b^{2} -4ac[/tex]
a=2,b=-8,c=7
Δ=(-8)²-4*2*7
Δ=64-56
Δ=8
√Δ=2√2
x1,2=-b±√Δ/2a
x1=8+2√2/4
x1=2(4+√2)/4
x1=4+√2/2
x2=4-√2/2
x| -∞ ................4-2√2...........4+2√2...........+∞
f(x)|.....↓↓↓↓.......0 ....↑↑↑↑↑...0.....↓↓↓↓↓....
