Question

Answer 1

a: =-(x^2+2x+5)

=-(x^2+2x+1+4)

=-(x+1)^2-4<=-4<0 với mọi x

b: =-(x^2-2x+4)

=-(x^2-2x+1+3)

=-(x-1)^2-3<=-3<0 với mọi x

c: =-2(x^2-x+1/2)

=-2(x^2-x+1/4+1/4)

=-2(x-1/2)^2-1/2<=-1/2<0 với mọi x

d: =-3(x^2-2/3x+1/3)

=-3(x^2-2/3x+1/9+2/9)

=-3(x-1/3)^2-2/3<=-2/3<0 với mọi x

Answer 2

\(a)A=-x^2-2x-5=-\left(x^2+2x+5\right)=-\left(x^2+2x+1+4\right)\)

\(=-\left(x+1\right)^2-4\le-4< 0\)

 

Answer 3

\(b)-x^2+2x-4=-\left(x^2-2x+4\right)=-\left(x^2-2x+1+3\right)=-\left(x-1\right)^2-3\le-3< 0\)

Answer 4

\(c)C=-x^2-x^2+2x-1=-x^2-\left(x-1\right)^2\le0\)

\(d)D=-2x^2-x^2+2x-1=-2x^2-\left(x-1\right)^2\le0\)