Calcule as equações incompletas por fatoração:
a) 2x² - 4x = 0
b) 3x² + 9x = 0
c) x² - 36 =0
d) 2x² - 50 = 0
Respostas
Resposta:
a) x²-49=0 a=1 b=0 c=-49
Δ = b² - 4.a.c
Δ = 0² - 4.1.-49
Δ = 0 + 196
Δ = 196
x = -b +- √Δ / 2a
x = +- √196 / 2.1
x = +- 14/2
x' = +14/2 x'' = -14/2
x' = +7 x'' = -7
b) x²=1
x² -1 = 0 a=1 b=0 c=-1
Δ = b² - 4.a.c
Δ = 0² - 4.1.-1
Δ = 0 + 4
Δ = 4
x = -b +- √Δ / 2a
x = +- √4 / 2.1
x = +- 2/2
x' = +2/2 x'' = -2/2
x' = +1 x'' = -1
c) 2x²-50=0 a=2 b=0 c=-50
Δ = b² - 4.a.c
Δ = 0² - 4.2.-50
Δ = 0 + 400
Δ = 400
x = -b +- √Δ / 2a
x = +- √400 / 2.2
x = +- 20/4
x' = +20/4 x'' = -20/2
x' = +5 x'' = -5
d) 7x²-7=0 a=7 b=0 c=-7
Δ = b² - 4.a.c
Δ = 0² - 4.7.-7
Δ = 0 + 196
Δ = 196
x = -b +- √Δ / 2a
x = +- √196 / 2.7
x = +- 14/14
x' = +14/14 x'' = -14/14
x' = +1 x'' = -1