Question

Resolva as equações de 2° grau:
a) ( x - 2 )² = 4 - 9x b) ( x + 1 ) ( x - 3 ) = -3

Answer 1

A)
2
x -4x-4 = 4 - 9x
2
x -4x+9x-4-4 =0
2
x +5x-8=0
2
A=1 ∆=5 -4.1.-8
B=5 ∆=25+32
C=-8 ∆= 57

X= ±√57



B)

(x+1) (x-3)=-3
2
X -3x+x-3=-3
2
X -2x-3=-3
2
X -2x-3+3=0
2
X -2x=0
2
A=1 ∆= -2 -4.1.0
B=-2 ∆=4-0
C=0 ∆=4
I
X = -(-2)+√4 2+2 4
--------------- = -------- = ---- = 2
2.1 2 2

II
X = -(-2)-√4 2-2 0
------------- = ------- = -----
2.1 2 2