The integer value of x for which x 2 + 19x + 92 is square of an integer are
Text Solution
Verified by ExpertsA
Let x 2 + 19x + 92 = m 2 , m
I
x 2 + 19x + 92 – m 2 = 0
x = 
∴ x
I
So, –19 ± ±
must be even integer
∴
must be odd integer
Let
= 2 k + 1; k
I
∴ 4m 2 – (2k + 1) 2 = 7
(2m – 2k – 1) (2m + 2k + 1) = 7
∴ 7 is prime
So, possibilities are
case
(i) 2m – 2k–1=1 & 2m + 2k + 1 = 7 then m = 2
(ii) 2m–2k–1 = 7 & 2m + 2k + 1 = 1 then m = 2
at m = 2 ⇒ x = –8, –11
(iii) 2m – 2k –1 = – 1 & 2m + 2k + 1 = –7
then m = – 2
(iv) 2m – 2k – 1= –7 & 2m + 2k + 1= –1 then m = –2
at m = – 2
x = – 8, – 11
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems