Test1.pdf @acer I have tried to duplicate your code ... but i still have an issue...

@acer thank you so much ...... I have just a last question ...How can i add b on the x axis ?

@Mac Dude you  thank  it's sure that will help, i have tried to change the bracket and put the parenthisis in the expression below, and use  solve(f(x)=0,x), but i still have some issues.