Question

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Answer 1

Resposta:

1)

a) x²+7x+12=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-7±\sqrt{7²-4.1.12})/2.1$

$(-7±\sqrt{49-48})/2$

$(-7±1)/2$

x1=(-7-1)/2=-8/2=-4

x2=(-7+1)/2=-6/2=-3

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b) x²+9x+20=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-9±\sqrt{9²-4.1.20})/2.1$

$(-9±\sqrt{81-80})/2$

$(-9±1)/2$

x1=(-9-1)/2=-10/2=-5

x2(-9+1)/2=-8/2=-4

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c)x²+11x+30=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-11±\sqrt{11²-4.1.30})/2.1$

$(-11±\sqrt{121-120})/2$

$(-11±1)/2$

x1=(-11-1)=2=-12/2=-6

x2=(-11+1)/2=-10/2=-5

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d)x²+8x+16=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-8±\sqrt{8²-4.1.16})/2.1$

$(-8±\sqrt{64-64})/2$

$(-8±0)/2$

x1=-8/2=-4

x2=-8/2=-4

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e)x²+10x+25=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-10±\sqrt{10²-4.1.25})/2.1$

$(-10±\sqrt{100-100})/2$

$(-10±0)/2$

x1=-10/2=-5

x2=-10/2=-5

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f)x²+12x+36=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-12±\sqrt{12²-4.1.36})/2.1$

$(-12±\sqrt{144-144})/2$

$(-12±0)/2$

x1=-12/2=-6

x2=-12/2=-6

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g)x²+6x+13=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-6±\sqrt{6²-4.1.13})/2.1$

$(-6±\sqrt{36-52})/2$

$(-6±\sqrt{-16})/2$

$(-6±4i)/2$

x1=(-6-4i)/2=-3-i

x2=(-6+4i)/2=-3+i

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

h)x²+6x+28=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-6±\sqrt{6²-4.1.28})/2.1$

$(-6±\sqrt{36-112})/2$

$(-6±\sqrt{-76})/2$

$(-6±\sqrt{-76})/2$

$(-6±2\sqrt{-19})/2$

$(-6±2i)/2$

x1=(-6-2i)/2=-3-i

x1=(-6+2i)/2=-3+i

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

i)x²+2x+10=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-2±\sqrt{2²-4..1.10})/2.1$

$(-2±\sqrt{4-40})/2$

$(-2±\sqrt{-36})/2$

$(-2±6i)/2$

x1=(-2-6i)/2=-1-3i

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

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

j)x²+6x+34=0

$(-b±\sqrt{b²-4.a.c})/2.a$

$(-6±\sqrt{6²-4.1.34})/2.1$

$(-6±\sqrt{36-136})/2$

$(-6±\sqrt{-100})/2$

$(-6±10i)/2$

x1=(-6-10i)/2=-3-5i

x2=(-6+10i)=2=-3+5i

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

2)

a)3x+9=0

3x=-9

x-9/3=-3

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

b)3x-4=0

3x=4

x=¾

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

c)2x+8=0

2x=-8

x=-8/2=-4

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

d)2x-8=0

2x=8

x=8/2=4

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

e)4x+12=0

4x=-12

x=-12/4=-3

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

f)4x-12=0

4x=12

x=12/4=3

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

g)5x+20=0

5x=-20

x=-20/5=-4

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

h)5x-20=0

5x=20

x=20/5=4

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

i)6x+12=0

6x=-12

x=-12/6=-2

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

j)6x-12=0

6x=12

x=12/6=2