定义如下运算:x11x12x13…x1nx21x22x23…x2nx31x32x33…x3n…xm1xm2xm3…xmn×y11y12y13…y1ky21y22y23…y2ky31y32y33…y3k

题目简介

定义如下运算:x11x12x13…x1nx21x22x23…x2nx31x32x33…x3n…xm1xm2xm3…xmn×y11y12y13…y1ky21y22y23…y2ky31y32y33…y3k

题目详情

定义如下运算:
x11x12x13x1n
x21x22x23x2n
x31x32x33x3n
xm1xm2xm3xmn
×
y11y12y13y1k
y21y22y23y2k
y31y32y33y3k
yn1yn2yn3ynk
=
z11z12z13z1k
z21z22z23z2k
z31z32z33z3k
zmkzmkzmkzmk

其中zij=xi1y1j+xi2y2j+xi3y3j+…+xinynj.(1≤i≤m,1≤j≤n,i.j∈N*).
现有n2个正数的数表A排成行列如下:(这里用aij表示位于第i行第j列的一个正数,i,j∈N*
a11a12a13a1n
a21a22a23a2n
a31a32a33a3n
an1an2an3ann
,其中每横行的数成等差数列,每竖列的数成等比数列,且各个等比数列的公比相同,若a24=1,a42=
1
8
a43=
3
16

(1)求aij的表达式(用i,j表示);
(2)若
a11a12a13a1n
a21a22a23a2n
a31a32a33a3n
an1an2an3ann
×
13
232
333
n3n
=
b11b12
b21b22
b31b32
bn1bn2
,求bi1.bi2(1≤i≤n,用i,n表示)
题型:解答题难度:中档来源:咸安区模拟

答案

(1)∵a42=class="stub"1
8
a43=class="stub"3
16
,且每横行成等差数列,
a4j=a42+(j-2)(class="stub"3
16
-class="stub"1
8
)=class="stub"1
16
j

a44=class="stub"4
16
=class="stub"1
4

又∵a24=1,a44=class="stub"1
4

q=class="stub"1
2
(∵q>0)
aij=a4j(class="stub"1
2
)i-4=class="stub"j
2i

(2)bi1=class="stub"1
2i
×1+class="stub"2
2i
×2+class="stub"3
2i
×3+…+class="stub"n
2i
×n

=class="stub"1
2i
(12+22+32+…+n2)=
n(2n+1)(n+1)
2i+1
bi2=class="stub"1
2i
×3+class="stub"2
2i
×32+class="stub"3
2i
×33+…+class="stub"n
2i
×3n

3bi2=class="stub"1
2i
×32+class="stub"2
2i
×33+…+class="stub"n-1
2i
×3n+class="stub"n
2i
×3n+1

②-①得 2bi2=-class="stub"1
2i
(32+33+…+3n)+class="stub"n
2i
×3n+1-class="stub"1
2i
×3
=-class="stub"1
2i
×
32-3n+1
1-3
+class="stub"n
2i
×3n+1-class="stub"1
2i
×3
=class="stub"1
2i+1
[(2n-1)3n+1+3]

bi2=class="stub"1
2i+2
[(2n-1)3n+1+3]

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