A) (a+b-c)^2 – (a-c)^2 – 2ab+2ab B) (a+b+c)^2 + (b+c-a)^2 + (c+a-b)^2 + (a+b-c)^2 Rút gọn jup mk a

0 bình luận về “A) (a+b-c)^2 – (a-c)^2 – 2ab+2ab B) (a+b+c)^2 + (b+c-a)^2 + (c+a-b)^2 + (a+b-c)^2 Rút gọn jup mk a”

1. $A) (a+b-c)^2 – (a-c)^2 – 2ab+2ab$

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

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

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

   $=b^2+2ab-2bc$

   $B)(a+b+c)^2+(b+c-a)^2 +(c+a-b)^2+(a+b-c)^2$

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

   $=a^2+b^2+c^2+a^2+b^2+c^2+a^2+b^2+c^2+a^2+b^2+c^2$

   $=4(a^2+b^2+c^2)$

   Bình luận