15.
If r and y are inserted between 4 and 16, so that
the resulting sequence becomes an AP, then
(a) x = 8, y = 12
(b) x = 10, y = 12
(c) r=8, y = 10
(d) x =10, y = 14
Full Marks:2
Answers
Answer:
x=8,y=12 Option(a)
Step-by-step explanation:
If r and y are inserted between 4 and 16
Then 4,x,y, 16 are in an AP
Let d is common difference
then
16 is 4th term
so 16=4+3d
3d=12,d=4
So x=4+4=8
and y=x+4=8+4=12
SOLUTION
TO CHOOSE THE CORRECT OPTION
If x and y are inserted between 4 and 16, so that
the resulting sequence becomes an AP, then
(a) x = 8, y = 12
(b) x = 10, y = 12
(c) x = 8, y = 10
(d) x = 10, y = 14
CONCEPT TO BE IMPLEMENTED
If in an arithmetic progression
First term = a
Common difference = d
Then nth term of the AP
= a + ( n - 1 )d
EVALUATION
Here it is given that x and y are inserted between 4 and 16
So the resulting sequence 4 , x , y , 16 becomes an AP
Let common difference = d
Then ,
x = 4 + d
y = 4 + 2d
16 = 4 + 3d
Now 16 = 4 + 3d gives
4 + 3d = 16
⇒ 3d = 12
⇒ d = 4
Thus we get
x = 4 + d = 4 + 4 = 8
y = 4 + 2d = 4 + 8 = 12
FINAL ANSWER
Hence the correct option is (a) x = 8 , y = 12
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