定义4△5 = 4 + 5 + 6 + 7 + 8 = 30,7△4 = 7 +

tikufree2019-12-17  21

问题 定义4△5 = 4 + 5 + 6 + 7 + 8 = 30,7△4 = 7 + 8 + 9 + 10 = 34,按此规律,(26△15) + (10△3)的值为( )。A. 528 B. 525 C. 423 D. 420

选项

答案A

解析(26△15) + (10△3) = (26 + 27 + 28+-----39 + 40) + (10 + 11 + 12) = (26+40)/2X 15 +33 = 528,故本题选A。
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