a)(x²)²-10x²+9=0
x²=t
t²-10t+9=0
a=1
b=-10
c=9
∆=b²-4*a*c
∆=(-10²)-4*1*9=100-34=64
∆=-b+✓∆/2a=-(-10)+8/2=18/2=9
t2=-b-✓∆/2a=-(-10)-8/2=1
la b si c tot așa faci cu ∆
b)
(x²)²+2x²-3=0
x²=t
t²+2x-3=0
a=1,b=2,c=-3
∆=b²-4*a*c=>2²-4*1*(-3)=4+12=16
x1=-2+4/2=1
x2=-2-4/2=-3
c)
(x2)²+2x²-8=0
t²+2t-8=0
a=1,b=2,c=-8
b²-4*a*c=>2²-4*1*(-8)=4+32=36
x1=-2+6/2=2
x2=-2-6/2=-4
