Question

a função f;[2,4]->R, definida por f (x)=-x2+2x+3 possui seu gráfico​

o valor máximo assumido pela função F é;

a) 6
b)5
c)4
d)3
e)1

Answer 1

$\boxed{\begin{array}{l}\sf f(x)=-x^2+2x+3\\\sf \Delta=b^2-4ac\\\sf\Delta=2^2-4\cdot(-1)\cdot3\\\sf\Delta=4+12\\\sf \Delta=16\\\sf o~valor~m\acute aximo~ocorre~no~y_V.\\\sf y_V=-\dfrac{\Delta}{4a}\\\\\sf y_V=-\dfrac{16}{4\cdot(-1)}\\\\\sf y_V=-\dfrac{16}{-4}\\\\\sf y_V=4\\\huge\boxed{\boxed{\boxed{\boxed{\sf\maltese~alternativa~c}}}} \end{array}}$