Question

if \( a\) and \( b\) are two vectors in linear vector space, prove Cauchy-Swartz inequality \( |a|.|b| \geq |a.b|\)

Answer 1

I have seen a proof that uses the idea that a quadratic
y= a x^2 + bx +c
is always positive for all values of x if its discriminate is negative: this means complex roots