PLEASE HELP I DON'T KNOW HOW TO DO THIS?!?!??!??!?!?!?
2 answers:
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We have
so this is indeed a difference of squares. Factorizing would give
making the answer D.
We can further factor the first term here and write
but that's clearly out of the scope of this question.
Answer:
- 494
Step-by-step explanation:
Breaking down the summation into it;s component parts
= 4k - k(k + 1) ← substitute k = 19
= (4 × 19 ) - 1.5 × (19 × 20)
= 76 - (1.5 × 380)
= 76 - 570
= 494