1.若x=156,y=144,½x²;+xy+½y²等于?2.25（a+b)&su_数学解答

1.若x=156,y=144,½x²;+xy+½y²等于?2.25（a+b)²-16(a-b)²等于?

人气：120 ℃　时间：2020-10-01 22:42:30

解答

,½x²;+xy+½y²=½(x²+2xy+y²)=½(x+y)²=½×300²=45000原式=[1.5(a+b)]²-[4(a-b)]²=(1.5a+1.5b)²-(4a-4b)²=[(1.5a+1.5b)+(4a-4b...