Question

Please explain to me how to do this

Answer 1

Sum = (number of terms) = 2 x (1st term + last term) 43

43. S200 = 200 = 2 × (1+200) = 100 201 = X 20,100

44 400 400 = 2 × (1+400) = 200 × 401 = 80,200

45 S800 = 800 = 2 × (1+800) = 400 × 801 = 320,400

46 S2000 = 2000 2 × (1+ 2000) = 1000 × 2001 = 2,001,000

Answer 2

see explanation

Explanation:

basically Gauss' method simplifies to

Sum = (number of terms) ÷ 2 × (1st term + last term)

43

S₂₀₀ = 200 ÷ 2 × (1 + 200) = 100 × 201 = 20,100

44

S₄₀₀ = 400 ÷ 2 × (1 + 400) = 200 × 401 = 80,200

45

S₈₀₀ = 800 ÷ 2 × (1 + 800 ) = 400 × 801 = 320,400

46

S₂₀₀₀ = 2000 ÷ 2 × (1 + 2000) = 1000 × 2001 = 2,001,000