If the derivative of f(x) is given by f′ (x)=−10x^3 +8ln(x) then for some number c,f(x) is concave up on (0,c) and is concave down on (c,[infinity]). What number is c ? If the derivative of f(x) is given by f′ (x)=4x^2 +7x+3 Find the largest critical number of the function f(x)=8x^3 +2x^2 +−19x