Respuesta :

y=3(x²+10x)+71
Now we need to complete square for (x²+10)
It should look like this
a²+2ab+b²=(a+b)²

y=3(x²+2*5x+5²)-3*5²+71
y=3(x+5)²-75+71
y=3(x+5)²-4
Vertex has coordinates x=-5, y=-4.
Vertex in this case is the extreme value (-5,-4)