llliujie
幼苗
共回答了15个问题采纳率:100% 举报
1.100 * (x^2 + 0.14x + k*0.01)
满足完全平方式,必须 x^2 + 2ax + a^2
2ax = 0.14 a = 0.07 k*0.01=a^2 =0.0049
k=0.49
100 x^2 + 14 x + 0.49 是 10(x+0.07)=10x+0.7 的平方
2.同上理,4x^2 + kx + 1 = 4(x^2 + k/4*x + 1/4)
a = 1/2 k/4 = 2*a = 1 k = 4
4x^2 + 4x + 1 是 2 (x+0.5) = 2x+1 的平方
但是注意 k=-4 同样成立.
k=4:k*k-2k+2 = 10
k=-4:k*k-2k+2 = 26
3.(2^48-1) = (2^24+1)(2^24-1)
(2^24-1) = (2^12+1)(2^12-1)
(2^12-1) = (2^6+1)(2^6-1)
2^6 = 64 (2*2*2 = 8,8*8=64)
(2^6+1) = 65
(2^6-1) = 63
(2^48-1) = (2^24+1)(2^12+1)(2^6+1) * 63
(2^48-1) = (2^24+1)(2^12+1)(2^6-1) * 65
数学是很有趣的,多做就会了.
1年前
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