Respostas

2013-11-06T14:10:05-02:00
x^{2}-7x+12=0
Temos de resolver por Bhaskara. 
$$ x=\frac{+7\pm\sqrt{(-7)^2-4x1x12}}{2}. $$
$$ x=\frac{+7\pm\sqrt{49-48}}{2}. $$
$$ x=\frac{+7\pm\sqrt{1}}{2}. $$
$$ x=\frac{+7\pm{1}}{2}. $$
$$ x'= 4. $$
$$ x''=3. $$
S: [3,4]

Espero ter ajudado
2013-11-06T14:21:34-02:00
A=1; b=-7; c=12
delta= b^2 -4 a.c = -7^2 -4(1).(12) = 49 - 48 = 1
x= -b +ou- raiz de delta tudo dividido por 2.a
x= 7 +ou- 1/2
x'= 7 + 1 /2 = 8/2 = 4
x"= 7-1 /2 = 6/2 = 3
S {3,4}