Meaning: x*(x-5)*6=396.
x ^ 2-5x-66 = 0。
(x- 1 1)(x+6)=0
Because x>0
So x- 1 1=0.
That is, x= 1 1, so the length is 1 1 cm and the width is 6 cm.
The square is represented by 2.
Have equal real roots.
Then the discriminant △ = (k+2) 2-16 (k-1) = 0.
That is, k 2- 12k+20 = 0.
That is, (k-2)(k- 10)=0.
k 1=2,k2= 10
When k=2, the equation is 4x 2-4x+ 1 = 0, and the solution is x 1=x2= 1/2.
When k= 10, the equation is 4x 2- 12x+9 = 0, and the solution is x 1=x2=3/2.