Respostas

2014-02-04T20:17:26-02:00
Δ = b² -4ac
Δ = 4² -4 *1 * (-21)
Δ = 16 + 84
Δ = 100
x' = (-b + √∆)/ 2a
(-4 + 10)/2 * 1
(-4 + 10)/2
6/2
3
x'' = (-b - √∆)/ 2a
(-4 - 10)/2 * 1
(-4 - 10)/2
-14/2
-7

S={-7,3}
3 3 3