Question

If x be real find the minimum value of 2x2 + 3x - 5

Answer 1

Min value of ax^2 + bx + c (where a>0) is -D/4a.
D = discriminant
$= {b}^{2} - 4ac$

Using this, min value of the expression is
$\frac{ - ( {3}^{2} - 4 \times 2 \times ( - 5)) }{4 \times 2}$
= -49/8