Question

设a-b=2+√2,c-b=2-√3,求a2(a的平方）+b2（b的平方）+c2（c的平方）-ab-bc-ac

Answer 1

a^2+b^2+c^2-ab-bc-ac

=(2a^2+2b^2+2c^2-2ab-2ac-2bc)/2

=[(a-b)^2+(a-c)^2+(b-c)^2]/2

=[6+4*2^(1/2)+7-4*3^(1/2)+5+2*6^(1/2)]/2

=9+2^(1/2)-2*3^(1/2)+6^(1/2)