find the x value

i have three function

part 1 : y=10 sqrt(x) + 20 x >= 8

part 2 : y=5x + 20 x <= x <= 8

part 3 : y=10 x < 0

how to find x value using matlab script ?

Answer 1

[KSSV]

I will show one for you, rest you should follow the same.

 % y=10 sqrt(x) + 20           x >= 8
 x = linspace(8,100) ; 
 y = 10*sqrt(x)+20 ;
 plot(x,y)