Question

the nth term of an AP an=4n-7.find its first term and common difference and 20th term. ​

Answer 1

Answer:

Nthterm=an=7−4n

First term=a1=7−4(1)=7−4=3

Second term a2=7−4(2)=−1

∴ Common difference=Secondterm−Firstterm

=(−1)−3=−4

Step-by-step explanation:

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Answer 2

Answer:

tn=4n-7.

n=1, t1 = 4-7 = -3. a=-3

n =2, t2 = 8-7= 1

n=3, t3 = 12-7 = 5

d = t3-t2 = t2-t1 = 5-1 = 1+3 = 4. d = 4

t20 = -3+19(4) = -3+76 = 73. t20 = 73