please help me more thanks ~~~~1 how many prime numbers p are there such that 199p+1 is a perfect square? A 0 B 1 C 2 D 4 E 8 2 HOW MANY PAIRS OF REAL NUMBERS (X,Y) SATISFY THE EQUATION (X+Y)^2=(X+3)(Y-3) A 0 B 1 C 2 D 4 E infinitely many3 What is the area of the polygon formed by all points (x,y) in the plane satisfying the inequality //x/-2/+//y/-2/
问题描述：
please help me more thanks ~~~~
1 how many prime numbers p are there such that 199p+1 is a perfect square?
A 0 B 1 C 2 D 4 E 8
2 HOW MANY PAIRS OF REAL NUMBERS (X,Y) SATISFY THE EQUATION (X+Y)^2=(X+3)(Y-3)
A 0 B 1 C 2 D 4 E infinitely many
3 What is the area of the polygon formed by all points (x,y) in the plane satisfying the inequality //x/-2/+//y/-2/
答
3 What is the area of the polygon formed by all points (x,y) in the plane satisfying the inequality //x/-2/+//y/-2/
答
1.199p+1=a^2=>(a+1)(a-1)=199pp is a prime.199 is also a prime.=>a+1=199 a-1=p or a+1=p a-1=199=>p=197,201(not a prime number so it is not a solution)So B is correct.2.(X+Y)^2=(X+3)(Y-3)=>x^2+2xy-(y-3)...