Suppose f(x) = ax-½+bx¯¹. It is given that f(1)=-12 and f(9)=4
Find the values of a and b.
p.s. -1/2 is an index of x, the above is not so clear cos i don't know how to type index in fraction form.
maths
2007-08-22 2:49 am
回答 (1)
2007-08-22 2:59 am
✔ 最佳答案
f ( x ) = ax-1 /2 + bx-1 f ( 1 ) = -12
a ( 1 )-1/2 + b ( 1 )-1 = - 12
a + b = -12 --- ( 1 )
f ( 9 ) = 4
a ( 9 )-1/2 + b ( 9 )-1 = 4
a / 3 + b / 9 = 4
3a + b = 36 --- ( 2 )
( 2 ) – ( 1 ) : 2a = 48
a = 24
Put a = 24 into ( 1 ).
24 + b = -12
b = -36
Hence a = 24 and b = -36.
參考: My Maths Knowledge
收錄日期: 2021-04-13 13:16:28
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