Resposta :
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x² - x - 20 = 0
x = -b ± √b² - 4ac
2a
x = -(-1) ± √(-1)² - 4(1)(-20)
2(1)
x = 1 ± √81
2
x = 1 ± 9
2
x' = 10 = 5
2
x" = -8 = -4
2
S = { 5 ; -4 }
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Att: MarcosPCV
x² - x - 20 = 0
x = -b ± √b² - 4ac
2a
x = -(-1) ± √(-1)² - 4(1)(-20)
2(1)
x = 1 ± √81
2
x = 1 ± 9
2
x' = 10 = 5
2
x" = -8 = -4
2
Att: MarcosPCV