Question

a) -x² + 4x+5
b) -7x-x²+4

Answer 1

a: =-(x^2-4x-5)

=-(x^2-4x+4-9)

=-(x-2)^2+9<=9

Dấu = xảy ra khi x=2

b: =-(x^2+7x-4)

=-(x^2+7x+49/4-65/4)

=-(x+7/2)^2+65/4<=65/4

Dấu = xảy ra khi x=-7/2