Conocido: ac+by=7 axx+byy=49 axxx+byyy=133 axxxx+byyyy=406, encuentre 1995(x+y)+6xy

De: ax+by=7 axx+byy=49 axxx+byyy=133 axxxx+byyyy=406, obtenemos

by=7-ax, byy=49-axx , byyy=133-axxx, sustituye paso a paso

ax^2+(7-ax)y=49 →ax=(49-7y)/(x-y) (1)

ax^3+(49-ax^2)y=133 →ax^2=(133-49y)/(x-y) (2)

ax^4+(133-ax^3 )y =406 →ax^3=(406-133y)/(x-y) (3)

(3)/(2)), (2)/(1) obtener

x=(406-133y)/(133-49y)=(133-49y)/(49-7y)

Solución: x=3,y=-1/2;x=- 1 /2,y=3

Fórmula original=1995*(3+1/2)+6*3*1/2=6991.5