Advertisements
Advertisements
प्रश्न
Which term of the A.P. `18, 15(1)/(2)`, 13, ... is – 47?
उत्तर
`18, 15(1)/(2)`, 13, ... is – 47
Let nth term is –47
a = 18, d = `15(1)/(2) - 18 = -2(1)/(2) = (-5)/(2)`
∴ –47 = a + (n – 1)d
⇒ –47 = `18 + (n - 1)((-5)/2)`
⇒ –47 – 18 = `(-5)/(2)n + (5)/(2)`
⇒ `-65 – (5)/(2) = (-5)/(2)n`
⇒ `(-135)/(2) = (-5)/(2)n`
∴ n = `(-135)/(2) xx (2)/(-5)` = 27
∴ –47 is 27th term.
APPEARS IN
संबंधित प्रश्न
Find three numbers in A.P. whose sum is 24 and whose product is 440.
The angles of a quadrilateral are in A.P. with common difference 20°. Find its angles.
Divide 96 into four parts which are in A.P. and the ratio between product of their means to product of their extremes is 15 : 7.
Q.2
Q.7
Q.8
Is –150 a term of 11, 8, 5, 2, .......?
Find the indicated terms in each of following A.P.s: 1, 6, 11, 16, …; a20
If the first term of an A.P. is – 18 and its 10th term is zero, then find its common difference.
The sum of three numbers in A.P. is 30 and the ratio of first number to the third number is 3 : 7. Find the numbers.
