等比数列{an}中,已知a7a8=5则a8a9a10a11a12=
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发布时间:2024-09-25 15:36
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热心网友
时间:2024-10-04 06:07
A7A12
=A7A7q^5
=(A7)^2q^5=5
A8A9A10A11
=A7q*A7q^2*A7q^3*A7q^4
=(A7)^4q^10
=[(A7)^2q^5]^2
=5^2
=25
热心网友
时间:2024-10-04 06:06
A7A12
=A7A7q^5
=(A7)^2q^5=5
A8A9A10A11
=A7q*A7q^2*A7q^3*A7q^4
=(A7)^4q^10
=[(A7)^2q^5]^2
=5^2
=25