a)x²+3=4x
x²-4x+3=0
∆=b²-4.a.c
∆=(-4²)-4.1.3
∆=16-12
∆=4
x= -b±√∆/2.a
x= -(-4)±√4/2.1
x= 4±2/2
x'= 4+2/2 x"= 4-2/2
x'= 6/2 x"= 2/2
x'= 3 x''= 1
s={1,3}
b)x²+x-20=0
∆=1²-4.1.(-20)
∆=1+80
∆=81
x= -1±√9/2.1
x= -1±9/2
x'= -1+9/2 x"= -1-9/2
x'= 8/2 x"= -10/2
x'= 4 x''= -5
S={4,-5}
c)2x²-98=0
2x²=98
2x=98/2
x²=49
x=±√49
x=±7
s={+7,-7}
