Answer:
x = 17
Step-by-step explanation:
in such a constellation (two beams from the same point of origin cut through the same circle) the relative relation between the segments of these beams to the overall length of the beam have to be the same :
7 × (7+x) = 8 × (8+13)
49 + 7x = 8 × 21 = 168
7x = 119
x = 17
11
(9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99)
Those numbers divisible by 9 are the multiple of 9; thus need to know how many multiples of 9 there are between 1 and 100:
100 ÷ 9 = 11 r 1 ÷ last multiple of 9 is 11 × 9 (= 99)
→ There are 11 - 1 + 1 = 11 numbers between 1 and 100 which are divisible by 9.
(They are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99.)
x = [-3 +/- √(3^2 - 4*1*2) ] / 2
= [- 3 + √( 1)] / 2 , [- 3 - √( 1)] / 2
= -2/2 , -4/2
= [-1, -2} answer
