The 3rd term of an AP is 3 and the 11th term is -21, find its first term and common difference.
Answers
Answered by
3
Step-by-step explanation:
a+2d=3---(equation 1)
a+10d=-21---(equation 2)
Subtracting equation 1 from equation 2
a-a+10d-2d=-21-3
8d=-24
d=-3
a=3-2(-3)
a=3+6
a=9
first term is a=9
common difference is d= -3
Answered by
1
Answer:
a+2d=3×10
a+10d=-21×2
10a+20d=30
2a+20d=-42
subtract
8a=72
a=9
put in any equation
9+2d=3
2d=12
d=6
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