\(D=-x^2+6x-11\)
\(D=-\left(x^2-6x+9\right)-2\)
\(D=-\left(x-3\right)^2-2\)
\(\le-2\)
Dấu "=" xảy ra khi \(x=3\)
\(E=5-8x-x^2\)
\(E=-\left(x^2-8x+16\right)+21\)
\(E=-\left(x-4\right)^2+21\)
\(\le21\)
Dấu "=" xảy ra khi \(x=4\)
E = 5 - 8x - x^2
= x^2 - 8x + 16 - 11
= x^2 - 2.x.4 + 4^2 - 11
= (x - 4)^2 - 11
đến đây dễ rồi
\(F=4x-x^2+1\)
\(F=-\left(x^2-4x+4\right)+5\)
\(F=-\left(x-2\right)^2+5\)
\(\le5\)
Dấu "=" xảy ra khi x=2
TL:
D=\(-\left(x^2-6x+9\right)-2\)
=\(-\left(x-3\right)^2-2\),
\(\le\) -2
=>Dmax=-2
hc tốt
