Step-by-step explanation:
A left Riemann sum approximates a definite integral as:

Given ∫₂⁸ cos(x²) dx:
a = 2, b = 8, and f(x) = cos(x²)
Therefore, Δx = 6/n and x = 2 + (6/n) (k − 1).
Plugging into the sum:
∑₁ⁿ cos((2 + (6/n) (k − 1))²) (6/n)
Therefore, the answer is C. Notice that answer D would be a right Riemann sum rather than a left (uses k instead of k−1).
I think 4/5 because if you multiply you get that!!!!!!
Hello :
x²+8x-3=0
(x² +2(4)x +4²) -4² -3 = 0
(x+4)²-19 = 0
(x+4)² = 19
x+4 = √19 or x+4 = - √19
x = √19 - 4 or x = -√19 - 4
Answer:
8
Step-by-step explanation: