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问题: 初三二次根式有关

设a1/b1 = a2/b2 = a3/b3 =.......= an/bn
(a1,a2,...,an, b1,b2,....,bn都是整数)
求证;/a1b1 + /a2b2 + /a3b3 +.....+ /anbn=
/a1+a2+a3+...+an * /b1+b2+b3+...+bn .

解答:

设a1/b1 = a2/b2 = a3/b3 =.......= an/bn
(a1,a2,...,an, b1,b2,....,bn都是整数)
求证;/a1b1 + /a2b2 + /a3b3 +.....+ /anbn=
/a1+a2+a3+...+an * /b1+b2+b3+...+bn .
解:
令:a1/b1 = a2/b2 = a3/b3 =.......= an/bn =t
则:a1=t×b1 a2=b×t2 ......an=t×an
√a1b1=b1√t √a2b2=b2√t.....an=bn√t
[√a1b1+√a2b2+.....+anbn]
=(√t)[b1+b2+...+bn]

√[a1+a2+a3+...+an] * √[b1+b2+b3+...+bn]
=√[(b1+b2+...+bn)×t]×√[b1+b2+....+bn]
=(√t)√[b1+b2+....+bn]