『HELP』初二数学,高手请进!在线等..

(a+b)*(a-b)=a^2-b^2=24
(a+b)^2=a^2+b^2+2ab
(a-b)^2=a^2+b^2-2ab
两式相减
8*8-3*3=4ab
ab=55/4

(a+b)^2=64
a^2+2ab+b^2=64(1)
(a-b)^2=9
a^2-2ab+b^2=9(2)
(1)-(2):
4ab=55
ab=13.75

a+b=8,所以(a+b)^2=a2+2ab+b2=8
a-b=3,所以(a-b)^2=a2-2ab+b2=9
即(a+b)^2－(a-b)^2＝4ab=-1
所以ab=-1/4

a+b+（a-b)=8+3=11
2a=11 a=5.5
a+b-(a-b)=8-3=5
2b=5 b=2.5
ab=13.75

∵(a+b)方=a方+b方+2ab=64
(a-b)方=a方+b方-2ab=9
∴(a+b)方-(a-b)方=4ab=64-9
ab=55/4