the value of x varies directly with y and inversely with z. when x=4, and y=12, z=6. what is the value of k?

7. if the value of x varies directly with the value of y, and x = 3 when y = 21. what is the valu y, and x = 3 when y = 21. what is the value of x when y = 105?

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Solve each quadratic equation by factoring and using the zero product property. [tex]x^2+6x+8=0[/tex]