Question

. Find the least value of f(x) if f(x)=3x2 - 6x-11​

Answer 1

Answer:

y=3*(x^2)+6*x+8

so dy/dx=6*x+6

=6*(x+1)

for minimum maximum dy/dx=0

6*(x+1)=0

x=-1

now on calculating second derivative of y at x=-1 is 6

since second derivative of y at x=-1 is greater than zero so at x=-1 function has a minimum

y(minimum)=3*(-1)^2+6*(-1)+8

=3*1–6+8

=5