1.任意两个连续奇数的平方差有什么特点?2.10^2-9^2+8^2-7^2.+2^2-1^23.(5-y)(-y-5)-(2y+1)(2y-1)

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1.任意两个连续奇数的平方差有什么特点?2.10^2-9^2+8^2-7^2.+2^2-1^23.(5-y)(-y-5)-(2y+1)(2y-1)

1.任意两个连续奇数的平方差有什么特点?2.10^2-9^2+8^2-7^2.+2^2-1^23.(5-y)(-y-5)-(2y+1)(2y-1)
1.任意两个连续奇数的平方差有什么特点?
2.10^2-9^2+8^2-7^2.+2^2-1^2
3.(5-y)(-y-5)-(2y+1)(2y-1)

1.任意两个连续奇数的平方差有什么特点?2.10^2-9^2+8^2-7^2.+2^2-1^23.(5-y)(-y-5)-(2y+1)(2y-1)
(2n+1)^2-(2n-1)^2
=(2n+1+2n-1)(2n+1-2n+1)
=8n
10^2-9^2+8^2-7^2.+2^2-1^2
=(10+9)(10-9)+(8+7)(8-7)+……+(2+1)(2-1)
=19+15+11+7+3
=(19+3)+(15+7)+11
=11*5
=55
(5-y)(-y-5)-(2y+1)(2y-1)
=(y-5)(y+5)-(2y+1)(2y-1)
=y^2-25-(4y^2-1)
=-3y^2-24