a)
x²-9=0
x²=9
x=3 v x=-3
b)
(x+2)(x-3)=0
x+2=0 v x-3=0
x=-2 v x=3
a) nie widać
b)
x²+x-2≥0
Δ= b²-4ac
Δ= 1 - 4 *1 * (-2)
Δ = 9
√Δ = 3
x1 = -b-√Δ /2a = -1-3 /2*1 = -4/2 = -2
x2 = -b+√Δ /2a = -1+3/2*1 = 2/2= 1
Na osi parabola ramionami do góry i:
x∈ ( -∞ ; -2> ∪ < 1 ; +∞)
