which of the following represents the left hand sum approximation of area under the curve y = f(t)?
ₙ₋₁
O lim ∑ f(t₁) Δt
ⁿ→[infinity] ᶦ⁼⁰
[infinity]
O lim ∑ f(t₁) Δt
ⁿ→[infinity] ᶦ⁼⁰
[infinity]
O lim ∑ f(t₁) Δt
ⁿ→[infinity] ᶦ⁼¹
ₙ
O lim ∑ f(t₁) Δt
ⁿ→[infinity] ᶦ⁼¹