diketahui f di tentukan dengan rumus f(x) =ax+b. jika f(1)=-1dan f(3)=7. tentukan rumus f(x)

f(x) = ax+b
f(1) = a.1 + b
-1 = a + b..........(1)

f(x) = ax + b
f(3) = a. 3 + b
7 = 3a + b........(2)

eliminasi b
-1 = a + b
7 = 3a + b
_________--
-8 = -2a
4 = a

eliminasi a
-1 = a + b | ×3 |
7 = 3a + b | ×1 |

-3 = 3a + 3b
7 = 3a + b
__________--
-10 = 2b
-5 = b
rumus f(x) = 4x + (-5)

semoga membantu