Question

Resolva as equações pela forma de bhaskara:
A)x²-8x+12=0
B)x²+2x-8=0
C)x²-5x+8=0
D)x²-x-12=0
E)3x²-12=0
F)x²+x-2=0

Answer 1

Resposta:

A)x²-8x+12=0

$(-b±\sqrt{b²-4ac})/2a$

$(-(-8)±\sqrt{(-8)²-4.1.12})/2.1$

$(8±\sqrt{64-60})/2$

$(8±\sqrt{4})/2$

$(8±2)/2$

x1=(8+2)/2=10/2=5

x2=(8-2)/2=6/2=3

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B)x²+2x-8=0

$(-b±\sqrt{b²-4ac})/2a$

$(-2±\sqrt{2²-4.1.(-8)})/2.1$

$(-2±\sqrt{4+32)/2$

$(-2±\sqrt{36})/2$

$(-2±\6)/2$

x1=(-2-6)/2=-8/2=-4

x2=(-2+6)/2=4/2=2

==================

C)x²-5x+8=0

$(-b±\sqrt{b²-4ac})/2a$

$(-(-5)±\sqrt{(-5)²-4.1.8})/2.1$

$(5±\sqrt{(25-32})/2$

$(5±\sqrt{-7})/2$

$(5±\sqrt{-7})/2$

$(5±\sqrt{7}i)/2$

x1=$(5+\sqrt{7}i)/2$

x1=$(5-\sqrt{7}i)/2$

==================

D)x²-x-12=0

$(-b±\sqrt{b²-4ac})/2a$

$(-1±\sqrt{(-1)²-4.1.(-12)})/2.1$

$(-1±\sqrt{1+48})/2$

$(-1±\sqrt{49})/2$

$(-1±7)/2$

x1=(-1+7)/2=6/2=3

x2=(-1-7)/2=-8/2=-4

==================

E)3x²-12=0

$(-b±\sqrt{b²-4ac})/2a$

$(0±\sqrt{0²-4.3.(-12)})/2.3$

$(0±\sqrt{144})/6$

$(0±\12)/6$

x1=12/6=2

x2=-12/6=-2

==================

F)x²+x-2=0

$(-b±\sqrt{b²-4ac})/2a$

$(-1±\sqrt{1²-4.1.(-2)})/2.1$

$(-1±\sqrt{1+8})/2$

$(-1±\sqrt{9})/2$

$(-1±3)/2$

x1=(-1+3)/2=2/2=1

x2=(-1-3)/2=-4/2=-2