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If the sum and product of the first three terms in an A.P. are 33 and 1155, respectively, then a value of its 11th term is:
Let us denote the three consecutive terms of the required arithmetic progression (A.P.) by $$a-d,\; a,\; a+d$$ where $$a$$ is the middle term and $$d$$ is the common difference. Choosing the terms in this symmetric form keeps the algebra simple because their sum depends only on $$a$$ while their product separates neatly into a factor of $$a$$ and a quadratic expression in $$d$$.
We are told that the sum of these three terms equals 33. Using the definition of sum we write
$$ (a-d)+a+(a+d)=33. $$
On the left-hand side the terms $$-d$$ and $$+d$$ cancel each other, leaving
$$ 3a = 33. $$
Dividing both sides by 3 gives
$$ a = \frac{33}{3}=11. $$
Next we use the information about the product of the same three terms, which is given as 1155. Writing the product explicitly we have
$$ (a-d)\,a\,(a+d)=1155. $$
First we substitute the value $$a=11$$ obtained above:
$$ (11-d)\,11\,(11+d)=1155. $$
Because multiplication is associative and commutative, we can take the constant factor 11 outside and recognise the remaining product as a difference of squares:
$$ 11\bigl[(11-d)(11+d)\bigr]=1155. $$
Using the algebraic identity $$ (x-y)(x+y)=x^{2}-y^{2} $$ with $$x=11$$ and $$y=d$$, we rewrite the bracketed term:
$$ 11\bigl[\,11^{2}-d^{2}\bigr]=1155. $$
We now compute the square of 11:
$$ 11\bigl[121-d^{2}\bigr]=1155. $$
To isolate the bracket we divide both sides by 11:
$$ 121-d^{2} = \frac{1155}{11}=105. $$
Rearranging gives a simple quadratic equation in $$d$$:
$$ d^{2}=121-105=16. $$
Taking square roots yields two possible real values for the common difference:
$$ d = \pm4. $$
So the required A.P. can rise by 4 each step (when $$d=+4$$) or fall by 4 each step (when $$d=-4$$). Both progressions satisfy the given sum and product conditions. We must now find the eleventh term and then see which value matches the options provided.
The general formula for the $$n^{\text{th}}$$ term of an A.P. whose first term is $$A_1$$ and common difference $$d$$ is
$$ A_n = A_1 + (n-1)d. $$
In our symmetric notation the first term is $$A_1 = a-d$$. Therefore the eleventh term is
$$ A_{11} = (a-d) + (11-1)d = (a-d) + 10d. $$
We already know $$a=11$$, so we substitute this value:
$$ A_{11} = 11 - d + 10d = 11 + 9d. $$
Now we consider the two possible values of $$d$$ separately.
Case 1: $$d=+4$$
$$ A_{11} = 11 + 9(4) = 11 + 36 = 47. $$
Case 2: $$d=-4$$
$$ A_{11} = 11 + 9(-4) = 11 - 36 = -25. $$
The question asks for “a value of its 11th term”, and among the four options given <-25> is the only one that appears in our calculation. The positive value <47> does not figure in the list. Therefore the admissible eleventh term consistent with the options is $$-25$$.
Hence, the correct answer is Option A.
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