Question

5 x ao quadrado + 21 x + 4 = 0​

Answer 1

∆=21²-4.5.4

∆=441-80

∆=361

x=-21+-19/10

x'=-21+19/10

x'=-2/10=-1/5

x"=-21-19/10

x"=-40/10=-4

S={-1/5, -4}