If k = ( 4 + 12 -1 ( 23 ) ) + ( 12 -1 ( 23 ) ), then the number of solutions of the equation -1(kx - 1) = -1x - -1x is .
Answer
1
Solution
Let -1 23 = 2 : 2 = 1 - 231 + 23 = 15 = 1 5
( 4 + ) = 1 + 1 51 - 1 5 = 5 + 1 5 - 1 = 3 + 52
Let -1 23 = 2 : 2 = 53
= 2 1 + 2 = 231 + 53 = 23 + 5 = 3 - 52
k = 3 + 52 + 3 - 52 = 3
Equation: -1(3x - 1) = -1x - -1x = 2 -1x - 2
Domain: -1 3x - 1 1 and -1 x 1 0 x 23
Taking sine: 3x - 1 = (2 -1x - 2 ) = - (2 -1x) = -(1 - 2x2)
2x2 - 3x = 0 x = 0 or x = 32 (rejected, outside domain)
Check x = 0: LHS = -1(-1) = - 2, RHS = 0 - 2 = - 2 ✓
number of solutions = 1
Answer: 1