Question

Resolva as esquaçaos de 2 grau em r

A- x²- 90 = 31

B- 5(x²-1) = (x²+1)

C- X (X + 2) = 2X + 25

Answer 1

A)
 
x² - 90 = 31
x² = 31 + 90
x² = 121
x = √121
x = + 11 e x = - 11

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B)
5.(x² - 1) = (x² + 1)
5x² - 5 = x² + 1
5x² - x² = 1 + 5
4x² = 6  (:2)
2x² = 3
x² =  3
        ---
         2
           ___
x = + √3/2
          ____
x = - √3/2


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C)
X.(X + 2) = 2X + 25
x² + 2x = 2x + 25
x² + 2x - 2x = 25
x² = 25
x = √25
x = + 5 e x = - 5