Question

http://hi.baidu.com/%D5%C5%C8%FE/album/item/0529ed334b65d2d4

Answer 1

a2x+b2 (1-x)≥[ax+b(1-x)]2

(a2-b2)x+ b2≥[(a-b)x+b]2

(a2-b2)x≥(a-b) 2x 2+2b(a-b)x

0≥(a-b) 2x(x-1)

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