1800-150-456-789
FlagBACK
Flag Magical Mathematics[Interesting Approach]> Find sum to n terms of series 3.1² + 4.2²...
question mark

Find sum to n terms of series 3.1² + 4.2² + 5.3²......

Bibek gautam , 6 Years ago
Grade 11
anser 1 Answers
Priyanka Bharti

Last Activity: 6 Years ago

3×1^2 + 4×2^2 + 5×3^2 +.......
= (1+2)×1^2 + (2+2)×2^2 + (3+2)×3^2 + ..    
= 1^3 +2×1^2 + 2^3 + 2×2^2 + 3^3 + 2×3^2 +...  . 
= ( 1^3 + 2^3 + 3^3 + . . . . .) +2(1^2 + 2^2 + 3^2 +... . )
Then apply formula and get the solution

Provide a better Answer & Earn Cool Goodies

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Other Related Questions on magical mathematics[interesting approach]

question mark
Given that (1+5x)⁴ = 1 + Px + Qx² + Rx³ +..... Find the values of P - 2Q + 3R
magical mathematics[interesting approach]
1 Answer Available

Last Activity: 2 Years ago

question mark
9 men and 15 boys working 10 hours a day can make 12 pillars in 42 days, in how many days will 12 men and 22 boys working 8 hours a day can make pillars 4 times the previous number?
magical mathematics[interesting approach]
1 Answer Available

Last Activity: 2 Years ago

question mark
In the given figure, PQ is a tangent at a point C to a circle with centre O. If AB is a diameter, find angle PCA + angle BCQ? 
magical mathematics[interesting approach]
0 Answer Available

Last Activity: 2 Years ago

question mark
for any two sets A and B (A-B)U(B-A)U (A intersection B)
magical mathematics[interesting approach]
0 Answer Available

Last Activity: 2 Years ago

question mark
If someone has got 150 out of 200 marks in term 1 exam and 160 out of 200 marks in term 2 exam then what is the percentage in  30:70 
magical mathematics[interesting approach]
0 Answer Available

Last Activity: 3 Years ago