(a+2b)^2=3,(a-2b)=2,a^2+4b^2=?,ab?

(a+2b)^2=3,(a-2b)=2,a^2+4b^2=?,ab?
(a+2b)^2=3,(a-2b)=2,a^2+4b^2=?,ab?

(a+2b)^2=3,(a-2b)=2,a^2+4b^2=?,ab?
即a²+4ab+4b²=3
a²-4ab+4b²=2
相加
2a²+8b²=5
a²+4b²=5/2
相减
8ab=1
ab=1/8