Thinking/Inquiry (10 marks) 5. Determine a quadratic function f (x) = ax2 + bx + c if its graph passes through the point (2, 19) and it has a horizontal tangent at (-1, -8). (5 marks) 6. Determine the equation of the tangent to the graph of f (x) = (x3 + 3x3 ) (-4x2+5) at x = 8. (5 marks) + '( x ) = ( x 3 + 3 x ] ) ( - 8 x ) + ( - ux > + 5 ) ( ax 3 + 75 x 3 1 ( x ) = =( 8 ) 3 + 3( 8 ) 3 ( - 8(8) ) +( 918) +5 ) ( 8 (5 ) 2 + 181 3 ) -=17380 + 175 ) + +. [ - 8.y Page 3 of 4