Question

if f(x) is a linear function such that f(1)=5 and f(4)=-7,then what is the value if f(-1)?

Answer 1

you know two points
(1,5) (4,7)
find slope and line equation

Answer 2

then evaluate at -1

Answer 3

imranmeah91 may I please have help.

Answer 4

Knowing 2 Y coordinates and 2 X coordinates you can get the slope of the line using
\[M = (y_{2} - y_{1}) \div (x_{2} - x_{1})\]
M = 2/3
Now knowing that we can solve for the y intercept
5 = (2/3) * 1 + b
Solve for b
B = 13/3

Now we know b and m, plug that into the equation for a line y=mx +b
y = ((2/3)*-1) + 13/3
y = (-2/3) +13/3
y = 11/3
Therefore f(-1) = 11/3