Question

Which term of an AP is 70 if first term is 120 and common difference is minus 5

Answer 1

a=120

d=-5,

an=a+(n-1)d

70=120+(n-1)(-5)

-50/-5=n-1

10=n-1

n=11

Answer 2

Answer:

Step-by-step explanation:

We know that

tn =a+(n-1)d

Given:

tn=70

a=120

d=-5

tn=120+(n-1)(-5)

70=120+(-5n)+5

70=125+(-5n)

70-125=-5n

(-55)=(-5n)

55=5n

n=55/5

n=11

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:. [ 11th term of an A.P is 70. ]

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