In an AP the first term is -5 and last term is 45 if sum of all numbers in the AP is 120 then how many numbers are there? what is the common difference?
The answer is 6,10
Please solve this with proper steps
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sum=1n÷2(a+l)
120*2=n(-5+45)
240=40n
n=6 ans.
l=a+(n-1)d
45=-5+(6-1)d
50=5d
d=10 ans.
120*2=n(-5+45)
240=40n
n=6 ans.
l=a+(n-1)d
45=-5+(6-1)d
50=5d
d=10 ans.
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