Question

Find the sum of ∑4/k=1 (-4k)

Answer 1

Answer:

Hello,

Answer C: -40

Step-by-step explanation:

$\displaystyle \sum_{k=1}^4\ (-4k)\\\\=-4*\sum_{k=1}^4\ k\\\\=-4*4*\dfrac{1+4}{2} \\\\=-4*5*2\\\\=-40$