Question

"9. If a is a non-zero constant, determine the vertex of the function y = -x2 + 4ax + 3 in terms of a. A) (2a, 4a2 + 3) B) (-2a, 12a2 + 3) C) (a, 3a2 + 3) D) (-a, -5a2 + 3) E) None of these

Answer 1

a -> - 1 ;
b -> 4a ;
c -> 3 ;
x = -b / (2a ) ;
x = -4a / ( - 2 ) ;
x = 2a ;
y = -(2a)^2 + (4a)×(2a) + 3 ;
y = -(4a^2) + 8a^2 + 3 ;
y = 4a^2 + 3 ;
The vertex of the function is ( 2a ; 4a^2 + 3 ) A).