Question

How much greater is the sum of the first 100 triangular numbers than the sum of the first 99 triangular numbers? Answer: It is bigger.

Answer 1

Answer:

First, a triangular number can be written as:

Tₙ = (n^2 + n)/2

where n is the number of our triangular number, n = 1 represents the first one, n = 2 represents the second one, etc.

The sum of the first 100 triangular numbers is:

S1 = (T₁ + T₂ + ... + T₉₉ + T₁₀₀)

The sum of the first 99 triangular numbers is:

S2 = (T₁ + T₂ + ... + T₉₉)

Then the difference will be:

D = S1 - S2 = (T₁ + T₂ + ... + T₉₉ + T₁₀₀) - (T₁ + T₂ + ... + T₉₉) = T₁₀₀

And we can find the value of T₁₀₀ if we use the equation for triangular numbers:

T₁₀₀ = (100^2 + 100)/2 = 5,050

Answer 2

Answer:

First of all I don't understand either, and I got it wrong.

Step-by-step explanation: