If x and y are positive integers for which 3x + 2y + xy = 115 + 7x, then what is x + y?
Hello Guest,
here's the answer:
3x+2y+xy=115+7x ,
ddx(3x)+ddx(2y)+ddx(xy)=ddx(115)+ddx(7x),
3+ddx(2y)+ddx(xy)=ddx(115)+ddx(7x),
3+ddy(2y)∗dydx+ddx(xy)=ddx(115)+ddx(7x) ,
3+ddy(2y)∗dydx+ddx(x)∗y+x∗ddx(y)=ddx(115)+ddx(7x) ,
3+ddy(2y)∗dydx+ddx(x)∗y+x∗ddx(y)=0+ddx(7x) ,
3+2∗dydx+ddx(x)∗y+x∗ddx(y)=0+ddx(7x) ,
3+2∗dydx+1y+x∗ddx(y)=0+ddx(7x) ,
3+2∗dydx+1y+x∗ddx(y)=0+ddx(7x) ,
3+2∗dydx+1y+x∗ddy(y)∗dydx=0+ddx(7x) ,
3+2∗dydx+1y+x∗ddy(y)∗dydx=ddx(7x) ,
3+2∗dydx+1y+x∗ddy(y)∗dydx=7 ,
3+2∗dydx+y+x∗ddy(y)∗dydx=7 ,
3+2∗dydx+y+x∗1∗dydx=7 ,
3+2∗dydx+y+x∗dydx=7 ,
2∗dydx+x∗dydx=7−3−y ,
(2+x)∗dydx=7−3−y ,
(2+x)∗dydx=4−y ,
dydx=4−y2+x ,
so the solution is: dydx=4−y2+x .
Straight