f.4 mathz.

1. given that the difference of two integers is 4, find the large number such that their product is the minimum

2. it is given that the vertex of the grape of y=-(x-h)^2 + k is A(1,4) , and cut the x-axis at B and C. Find the area of ABC

3.if a is not equal to B , a=a^2-7 and B=B^2-7 , find the value of (a+2)(B+2)