(2) By an = 2n? 1, bn = an2+log2an = 4n-1+(n-1) is known, and the sum of the first n items of the sequence {bn} can be obtained by using the grouping summation method.
Solution: Solution: (1) Let the common ratio {an} of geometric series be q, then an=a 1qn- 1.
By the known a1a3+2a4a4+a3a5 = (a2+a4) 2 =100,
an > 0,(n∈N*),
∴a2+a4= 10,
∵4 is the equal ratio median of a2 and a4,
∴a2a4=42= 16,
A2 and a4 are two roots of the equation x2- 10x+ 16=0.
∵q> 1,∴a2=2,a4=8,
∴
a 1q=2 a 1q3=8
The solution is a 1= 1, and q=2.
∴an=2n? 1.
(2)∫an = 2n? 1,
∴ bn = an2+log2an =4n- 1+(n- 1),
The sum of the first n terms of the sequence {bn}
sn =( 1+4+42+…+4n- 1)+( 1+2+3+…+n- 1)= 4n? 1/3 +n(n? 1) /2