Question

a-b=2+根号3 b-c=2-根号3 a平方+b平方+c平方-ab-bc-ac=

Answer 1

∵（A-B）+（B-C）=A-C=2根号3

（A-B)^2+（A-C)^2+(B-C)^2

=A^2+B^2-2AB+A^2+C^2-2AC+B^2+C^2-2BC

=2A^2+2B^2+2C^2-2AB-2AC-2BC

=2(A^2+B^2+C^2-AB-AC-BC)

=(根号3+根号2）^2+（根号3-根号2）^2+（2根号3）^2

=3+2+2根号6+3+2-2根号6+12

=22

∴A^2+B^2+C^2-AB-AC-BC=11