4. Using implicit differentiation, find a dxz for yz = 7x Circle the letter that best answers each question. Show ALL supporting work and computations that lead to your answer. 5. For what values of x does the curve y2 - x3 - 15x2 = 4 have horizontal tangent lines? (A) x = -10 only (B) x = 0 only (C) x = 10 only (D) x =-10 and x = 0 only (E) x = -10 , = 0 , and x = 10Implicit Differentiation 25 No Calc Show ALL supporting work and computations that lead to your answer. Include correct notation lv/If :1: = 1 | my then nd the equations of all tangent lines tn the curve when :1: = 1.