Solving math problems in the second day of junior high school. Please write down the analysis and solutions of the following three problems.

1 proves that b2-4ac= 1 has two real roots, so it can be proved.

Or decompose the equation into (x-t)*(x-t-2)=0, two real roots x=t and x=t+2.

2. Bring the two real roots into the equation y=-2/t, and the image is a hyperbola of quadrant 2 and quadrant 4.

According to the image, when t is greater than or equal to 1 or less than or equal to -2/3, y is -2.

Make a straight line with y=-t/2, and the intersection with hyperbola is the answer. At this time t= plus or minus 2.

3. If diagonal lines are used, the diamond area is half of the product of two diagonal lines. s=(t+2)*t/2= 12。

T=4，t+2=6。 According to Pythagorean Theorem, unilateral length a= root (2*2+3*3) and perimeter =4* root 13.