Question

coordenadas do vértice da parábola f(x)=x²+3x-1=

Answer 1

Boa tarde!

Solução!

$f(x)= x^{2} +3x-1\\\\\\ V\left ( \dfrac{b}{-2a}, \dfrac{\Delta}{-4a} \right )\\\\\\ a=1\\\\ b=3\\\\\ c=-1$


$x_{V}= \dfrac{3}{-2.1}\\\\\\\\ x_{V}= \dfrac{3}{-2}\\\\\\\\ \boxed{ x_{V}=-\dfrac{3}{2}}\\\\\\\\\\\\ y_{V}= \dfrac{3^{2}-4.1.-1 }{-4.1}\\\\\\\ y_{V}= \dfrac{9+4 }{-4}\\\\\\\ \boxed{y_{V}= -\dfrac{13}{4}}\\\\\\\\\\ V\left (- \dfrac{3}{2} , -\dfrac{13}{4} \right )$

Boa tarde!
Bons estudos!

Answer 2

f (x) = x² + 3x - 1

a = 1; b = 3; c = -1

Δ = b² - 4ac
Δ = 3² - 4 . 1 . (-1)
Δ = 9 + 4
Δ = 13

Vértice de x:               Vértice de y:
Xv = - b / 2a               Yv = - Δ / 4a
Xv = - 3 / 2 . 1            Yv = - 13 / 4 . 1
Xv = - 3 / 2                 Yv = - 13 / 4
Xv = -1,5                    Yv = -3,25

Como (x, y), as coordenadas do vértice são: V (-1.5 , -3.25).

Espero ter ajudado. Valeu!