FORECAST(x,known_y's,known_x's)
FORECAST . y x (@x).
@known_x @known_y , FORECAST #N/A!. @known_x 0, FORECAST #DIV/0!.
Excel.
, A1, A2, ..., A5 11.4, 17.3, 21.3, 25.9 40.1, B1, B2, ... B5 23.2, 25.8, 29.9, 33.5 42.7.
FORECAST(7,A1:A5,B1:B5) -10.859397661.
INTERCEPT, TREND.