Question

Achar as raízes das equações:
a) x² - x - 20 = 0
b) x² - 3x -4 = 0
c) x² - 8x + 7 = 0

Answer 1

Resposta:

X² - 8x + 7 = 0

a = 1 b = -8 c = 7

Δ = b² - 4ac

Δ = (-8)² - 4.(1).(7)

Δ = 64 - 28

Δ = 36

x = \frac{-b \frac{+}{-} \sqrt{b^2-4ac} }{2a}

x= \frac{-(-8) \frac{+}{-} \sqrt{36} }{2}

x = \frac{8 \frac{+}{-} 6}{2}

x' = \frac{8+6}{2}

x' = 7

x" = \frac{8-6}{2}

x" = 1

S = {1,7}