Show that if?(()')c'is a constant and 'f'is a differentiable function, thenddx[cf(x)]=cddxf(x)The cost of producing 'x' ounces of gold from a new gold mine isC=f(x) dollars.a. For what values of'x'is the function f(x)=|x2-9| differentiable?Find a formula for ?(()')f'.b. Sketch the graphs off and f';