Answer:
a*(20-a)
Step-by-step explanation:
Let's assume that the length of the garden is a the width is b and the area is s.
b = 40/2 - a = 20-a
s =a*(20-a)=-a^2+20a=-(a-10)^2+100
then,
when a=10, max(-(a-10)^2) =0, max(s)=100
I think the third one is the answer
(x+2y+z) (x-2y-z)
= x^2 - 2xy - xz + 2xy - 4y^2 - 2yz + xz - 2yz - z^2 = x^2 - 4y^2 - 4yz -z^2
Hope it helped!
That is in its simpist form already, trick question.
