4*7*10+7*10*13+10*13*16+……+(3n+1)(3n+4)(3n+7)=

Answer 1

the general term is 27n³+108n²+117n+28

sum of 28 n times equals 28n

sum of 117n summed n=1 to n=n equals 117[(n(n+1))/2]

sum of 108n² summed n=1 to n=n equals [108{n(2n+1)(n+1)/6]

sum 0f 27n³ summed n=1 to n=n equals 27[n(n+1)/2]²

example:n=4,

sum of general term n=1 to n=4 = 28(4)+117(10)+108(30)+27(100)=7222