Mathematics
The sum of the squares of two consecutive multiplies of 7 is 637.
Taking the bigger number x a positive number, find the smaller of these two angles.
Answer
Let the multiplies of 7 be 7x and 7(x + 1).
It is given that the sum of the squares of two consecutive multiplies of 7 is 637.
⇒ (7x)2 + [7(x + 1)]2 = 637
⇒ 49x2 + [7x + 7]2 = 637
⇒ 49x2 + 49x2 + 72 + 98x - 637 = 0
⇒ 98x2 + 49 + 98x - 637 = 0
⇒ 98x2 + 98x - 588 = 0
⇒ x2 + x - 6 = 0
⇒ x2 + 3x - 2x - 6 = 0
⇒ x(x + 3) - 2(x + 3) = 0
⇒ (x + 3)(x - 2) = 0
⇒ (x + 3) = 0 or (x - 2) = 0
⇒ x = -3 or x = 2
It is given that x is bigger positive number.
So, the multiplies of 7 is 7 x 2 = 14 and 7(2 + 1) = 7 x 3 = 21
Hence, the smaller angle is 14.