Question

Resolva as equações incompletas:
a)b) (x+5)(x-6)=51-x
b)x²+2=2

Answer 1

(x+5)(x-6)= 51-x

x²-6x+5x-30-51+x=0
x²-81=0

x=$\sqrt{81}$

x=9

b) x²+2=2

x²+2-2=0

x²= 0

x=$\sqrt{0}$

x=0 

Answer 2

a (x+5)(x-6)=51-x
x² - 6x + 5x - 30 = 51 - x
x² - 6x + 5x + x - 30 - 51 =0
x² -6x + 6x - 81=0      elimina - 6x e + 6x , são iguais de sinais diferentes.
x² - 81 = 0
x² = +81
x = ± √81
x = ± 9
S{-9 ; + 9}

b)x²+2=2
x² = 2 - 2
x² = 0
x= ± √0
x= ± 0

S{0}