if ap if a3= 10 d=2 than a6 =
Answers
Answered by
2
Answer:
a6=20 .......
..
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Answered by
1
Step-by-step explanation:
11th
Maths
Sequences and Series
Arithmetic Progression
If for an A.P. a1,a2,a3,.....
MATHS
If for an A.P. a
1
,a
2
,a
3
,.....,a
n
,....,a
1
+a
3
+a
5
=−12 and a
1
a
2
a
3
=8 then the value of a
2
+a
4
+a
6
equals to
MEDIUM
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ANSWER
Given:a
1
+a
3
+a
5
=−12
a+a+2d+a+4d=−12
⇒3a+6d=−12
⇒a+2d=−4 .......(1)
a
1
a
2
a
3
=8
⇒a(a+d)(a+2d)=8
⇒a(a+d)×−4=8 from (1)
⇒a(a+d)=−2
⇒(−4−2d)(−4−2d+d)=−2
⇒−2(2+d)(−d−4)=−2
⇒(d+2)(d+4)=−1
⇒d
2
+6d+8+1=0
⇒d
2
+6d+9=0
⇒d
2
+2×3d+9=0
⇒(d+3)
2
=0
⇒d=−3
Put d=−3 in (1)
a+2×−3=−4
⇒a=−4+6=2
∴a=2,d=−3
a
2
+a
4
+a
6
=a+d+a+3d+a+5d=3a+8d=3×2+8×−3=6−24=−18
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