The first-order function y = KX + B, when x = 4, y = 9; when x = 6, y = 3, what is k What is the value of y when x = 1

The first-order function y = KX + B, when x = 4, y = 9; when x = 6, y = 3, what is k What is the value of y when x = 1

k=-3 b=21 x=1 y=18

It is known that the value of primary function y = KX = B is 9 when x = - 4 and 3 when x = 6. Find the value of K and B
Urgency, speed

9=-4k+b
3=6k+b
Two phase subtraction
10k=-6
k=-3/5
Get by substitution
9=-4*(-3/5)+b
9=12/5+b
b=(45-12)/5=33/5

It is known that the value of the first-order function y = KX + B is 5 when x = 3 and - 9 when x = - 4

From the meaning of the problem, we can get 5 = 3K + B − 9 = − 4K + B, the solution is k = 2B = − 1, so the analytic formula of this first-order function is: y = 2x-1