Question

Jika a=2+ akar 7 dan b=2- akar 7,nilai a pangkat 2 + b pangkat 2 -4

Answer 1

(a^2+b^2-4) = (2+√7)^2+(2-√7)^2-4
= (4+4√7+7)+(4-4√7+7)^ -2
=(11+4√7)+(1/(11-4√7))
= [(11+4√7)(11-4√7)+1]/11-4√7
= (121 -112+1)/11-4√7
= 10/11-4√7