Chapter 5: Exercises with Solutions

Chapter 5Quadratic Functionsheight = 0 =⇒ h(t) = 0 =⇒ −16t 2 + 63t + 42 = 0Now use either the quadratic formula or the ZERO routine on your calculator to findthe approximate solutions of this equation:x = −b ± √ b 2 − 4ac2a= −63 ± √ 63 2 − 4(−16)(42)2(−16)= −63 ± √ 6657−32≈ −0.581, 4.518Since −0.581 is meaningless in the context of the question, the approximate answer is4.518. Rounded to the nearest hundredth of a second, the answer is 4.52.53. If the y-axis is oriented with the positive direction upward, and the 0 mark is setat ground level, then the height (in feet) of the penny after t seconds is given by thefunctionNote thath(t) = −16t 2 − 16t + 68height = 0 =⇒ h(t) = 0 =⇒ −16t 2 − 16t + 68 = 0Now use either the quadratic formula or the ZERO routine on your calculator to findthe approximate solutions of this equation:x = −b ± √ b 2 − 4ac2a= 16 ± √ (−16) 2 − 4(−16)(68)2(−16)= 16 ± √ 4608−32≈ −2.621, 1.621Since −2.621 is meaningless in the context of the question, the approximate answer is1.621. Rounded to the nearest hundredth of a second, the answer is 1.62.Version: Fall 2007