Extrapolates future values based on existing x and y values.
FORECAST.LINEAR(Value; DataY; DataX)
Value is the x value, for which the y value on the linear regression is to be returned.
DataY is the array or range of known y's.
DataX is the array or range of known x's.
=FORECAST.LINEAR(50;A1:A50;B1;B50) returns the Y value expected for the X value of 50 if the X and Y values in both references are linked by a linear trend.