maths~~~~~~~

假設餘式=ax+b:

f ( x ) = ( x - 5 )( x + 2 ) Q ( x ) + ax + b

f (5) = 9

5a + b = 9 --- ( 1 )

f (-2) = -5

-2a + b = -5

b = 2a - 5 --- ( 2 )

代(2)入(1),

5a + 2a - 5 = 9

7a = 14

a = 2

b = 2 ( 2 ) - 5 = -1

所以餘式: 2x-1。