Answer:
√841
Step-by-step explanation:
You would use pythagorean theorem to solve this problem:
a² + b² = c²
a = 20 b = 21
20² + 21² = 400 + 441 = 841
√841
Answer: d
Step-by-step explanation:
I know this doesn't help but i'm on the same thing and i just don't know
Answer:
d=-4 and a=10
Step-by-step explanation:
The sum of a arithmetic sequence is given by (n/2)*(2a+(n-1)d). Comparing coefficients with the given Sn, we have; a-d/2=12 and d/2=-2, d=-4 and a=10.
