Question

已知一次函数的图像经过（2,-4）（4,1）两点,（1）求一次函数表达式

Answer 1

let y = ax+b

(2,-4)

-4 = 2a+b

b= -4-2a ----(1)

(4,1)

1=4a+b

= 4a-4-2a ( from (1))

2a = 5

a = 5/2

b= -4-2(5/2) = -9

一次函数:y = (5/2)x - 9