if s10 =55 and s9=45 find a10
Answers
Answered by
1
Answer:
10
Step-by-step explanation:
S10-S9=A10
therefore a10 = 10 (55-45)
Answered by
1
Step-by-step explanation:
Sn= n/2[2a+(n-1)d]
S10=10/2[2a+(10-1)•d]
S10=5[2a+9d] =55‐--‐(i)
S10=2a+9d=55/5=11(by taking 5 to RHS)
Now,
S9=9/2[2a+(9-1)d]=45
S9=2a+8d=45/4.5=10--------(ii)
Then,subtracting both equations
2a+9d=11
-2a+8d=10
---------------
1d=1
Substitute the value in equation (i)
2a+9•1=11
2a=11-9=2
a=2/2=1
Now = a10=a+(n-1)d
a10= 1+(10-1)1
a10=1+9=10 (ans)
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