Question

How to find the minimum value of an expression

Answer 1

Your answer is positive

Answer 2

f(x)=9x²+24x+1
f(x)=(3x)²+ 2×3x× 4 + 1
= (3x)²+2×3x×4 +16 -16 +1
=. ( 3x+4)² -15. -------(1)
then (3x+4)² ≥0
least value of (3x+4)² is 0
putting in equation 1
= 0-15 =-15
- 15 is the least value