If Ss= 32, S4 = 28~~What is ts=?a)36b)24c)8d)4Correct answer is option...
Given, Ss= 32 and S4 = 28
To find, ts=?
We know that the sum of an arithmetic progression (AP) is given by the formula:
Sn = n/2[2a + (n-1)d]
where Sn is the sum of first n terms, a is the first term, d is the common difference and n is the number of terms.
Let's find the common difference (d) of this AP.
S4 = 4/2[2a + (4-1)d] = 2[2a + 3d] = 4a + 6d
Given that S4 = 28, we have:
4a + 6d = 28
Similarly, for Ss, we have:
Ss = s/2[2a + (s-1)d] = s/2[a + a + (s-1)d] = (s/2)[2a + (s-1)d]
Given that Ss = 32, we have:
(s/2)[2a + (s-1)d] = 32
Dividing both sides by 4, we get:
(s/8)[2a + (s-1)d] = 8
Now, we can substitute the value of a + 3d from the equation 4a + 6d = 28 into the above equation, to get:
(s/8)[2(a + 3d) + (s-4)d] = 8
Simplifying this, we get:
s^2 - 16s + 64 = 0
This is a quadratic equation that can be factored as:
(s-8)(s-8) = 0
Therefore, the only possible value of s is 8.
Hence, the answer is option D, ts = 4.
If Ss= 32, S4 = 28~~What is ts=?a)36b)24c)8d)4Correct answer is option...
See use formula of sum of nth term u will get two equations then slove it..