Find the number of roots of the equation for .
Hint:
Inspiration Aniket Sanghi
Bonus: Find total number of roots for
All of my problems are original
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Graph of l o g 1 0 ∣ x ∣
Graph of c o s ( s i n ( x ) )
So, we can see that c o s ( s i n ( x ) ) ∈ [ c o s ( 1 ) , 1 ]
So, we have to find for what values of x , l o g 1 0 ∣ x ∣ ∈ [ c o s ( 1 ) , 1 ]
c o s ( 1 ) ≤ l o g 1 0 ∣ x ∣ ≤ 1
1 0 c o s ( 1 ) ≤ ∣ x ∣ ≤ 1 0
1 0 2 c o s ( 1 ) ≤ ∣ x ∣ ≤ 1 0 0
1 2 ≤ ∣ x ∣ ≤ 1 0 0
4 π ≤ ∣ x ∣ ≤ 3 1 . 8 3 π
As it is mentioned for ∣ x ∣ ≤ 3 1 π
4 π ≤ ∣ x ∣ ≤ 3 1 π
− 3 1 π ≤ x ≤ − 4 π or 4 π ≤ x ≤ 3 1 π . . . . . . . . . . . ( 1 )
Now, for each x ∈ [ n π , ( n + 1 ) π ] in ( 1 ) , there are 2 intersections
So, there are a total of ( ( 3 1 − 4 ) × 2 ) × 2 = 1 0 8 intersections
Here is a graph combining both equations