y = -2(x-4)2-6
= -4(x-4) - 6
= -4x + 16 -6
y = 10- 4x
now if x is positive, x >= 0
then max value of y will be when x will nr minimum
so max y = 10- 4×0 = 10
so y = 10 at x =0 for x >=0
if x < 0 then
y will be increasing as x gets increase towards more negative. so max of y will be decided when x reaches to max negative.
