Question

determine a raiz de cada equação do segundo grau incompletas x²-15x=0

x2-81=0​

Answer 1

Resposta:

a) x² - 15x = 0

ax² + bx + c

a = 1 , b = - 15, c = 0

∆ = b² - 4.a.c

∆ = (-15)² - 4.1.0

∆ = 225 - 0

∆ = 225

x = - b ± √∆ / 2.a

x = -(-15) ± √225 / 2.1

x = 15 ± 15 / 2

x1 = 15 - 15 = 0 ÷ 2 = 0

x2 = 15 + 15 = 30 ÷ 2 = 15

raízes:

x¹ = 0

x² = 15

b) x² - 81 = 0

ax² + bx + c

a = 1, b = 0, c = - 81

∆ = b² - 4.a.c

∆ = (0)² - 4.1.(-81)

∆ = 0 - 4.(-81)

∆ = 0 - ( 324)

∆ = 0 + 324

∆ = 324

x = - b ± √∆ / 2.a

x = -(-0) ± √324 / 2.1

x = 0 ± 18 / 2

x1 = 0 + 18 = 18 ÷ 2 = 9

x2 = 0 - 18 = (-18) ÷ 2 = - 9

raízes:

x¹ = 9

x² = - 9