# 22) 4 + x(x-4) = X(R 1,4)23) x ( x + 3) - 40 = 0 (R: 5, -8)24) x² + 5x+6=0 (R=-2, -3).25) x² - 7x + 12 = 0 (R:3,4)26) X² + 5x + 4 = 0 (R:-1,-4)27) 7x² + x + 2 = 0 (vazio)28) x² - 18x + 45 = 0 (R:3, 15)29) -X² - X + 30 = 0 (R:-6, 5)30) x² - 6x + 9 = 0 (R:3)​

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## 1 Resposta

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Resposta:

22)

4+x²-4x=x

x²-5x+4=0

x'=[5+√(25-16)]/2 =(5+3)/2=4

x''=[5-√(25-16)]/2 =(5-3)/2=1

23)

x ( x + 3) - 40 = 0

x²+3x-40=0

x'=[-3+√(9+160)]/2 =(-3+13)/2=5

x''=-3-√(9+160)]/2 =(-3-13)/2=-8

24)

x² + 5x+6=0

x'=[-5+√(25-24)]/2 =(-5+1)/2=-2

x''=[-5-√(25-24)]/2 =(-5-1)/2=-3

26)

x² + 5x + 4 = 0

x'=[-5+√(25-16)]/2 =(-5+3)/2=-1

x''=[-5-√(25-16)]/2 =(-5-3)/2=-4

27)

7x² + x + 2 = 0

Δ=1-56 < 0 , ñ tem raízes reais

28)

x² - 18x + 45 = 0

x'=[18+√(324-180)]/2 =(18+12)/2=15

x''=[18-√(324-180)]/2 =(18-12)/2=3

29)

-x² - x+ 30 = 0

x'=[1+√(1+120)]/2 =(1+11)/(-2)=-6

x''=[1-√(1+120)]/2 =(1-11)/(-2)=5

30)

x² - 6x + 9 = 0

x'=[6+√(36-36)]/2 =(6+0)/(2)=3

x''=[6-√(36-36)]/2 =(6-0)/(2)=3

x'=x''=3

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