Question

PARÁBOLA! NECESITO SABER QUÉ HICE MAL?

Answer 1

Y = 2x² - x - 15

Encontrando "x" usando:

x = [ -b ± √( b² - 4ac )] / 2a

Donde:
a = 2
b = -1
c = -15

x = [ -( -1 ) ± √( (-1)² - 4(2)(-15) )] / 2(2)
x = [ 1 ± √( 1 + 120 )] / 4
x = [ 1 ± √( 121 )] / 4
x = ( 1 ± 11 ) / 4

Encontrando "x1" y "x2"

x = ( 1 + 11 ) / 4
x = ( 12 ) / 4
x = 3

x = ( 1 - 11 ) / 4
x = ( - 10 ) / 4
x = -5 / 2 = - 2.5

Vértice → x = - b / 2a

x = - ( -1 ) / 2(2)
x = 1 / 4 = 0.25

Y( 1/4 ) = 2( 1/4 )² - ( 1/4 ) - 15
Y( 1/4 ) = 2( 1/16 ) - 61/4
Y( 1/4 ) = 1/8 - 61/4 = - 121/8 = -15.13

Punto del vértice → ( 1/4, -121/8 )

¡Espero haberte ayudado, saludos!