Question 1193889
Find the quadratic function that fits the data points (1,6) (-1,2) and (3,34).
<pre>Equation of a PARABOLA: <font size = 4><font color = red><b>y = ax<sup>2</sup> + bx + c</font></font></b>
                        <font size = 4><font color = red><b>6 = a(1)<sup>2</sup> + b(1) + c</font></font></b> ----- Substituting (1, 6) for (x, y) 
                        <font size = 4><font color = red><b>6 = a + b + c</font></font></b> ---- eq (i)

                        <font size = 4><font color = red><b>y = ax<sup>2</sup> + bx + c</font></font></b>
                        <font size = 4><font color = red><b>2 = a(- 1)<sup>2</sup> + b(- 1) + c</font></font></b> ----- Substituting (- 1, 2) for (x, y) 
                        <font size = 4><font color = red><b>2 = a - b + c</font></font></b> ---- eq (ii)

                        <font size = 4><font color = red><b>y = ax<sup>2</sup> + bx + c</font></font></b>
                       <font size = 4><font color = red><b>34 = a(3)<sup>2</sup> + b(3) + c</font></font></b> ----- Substituting (3, 34) for (x, y) 
                       <font size = 4><font color = red><b>34 = 9a + 3b + c</font></font></b> ---- eq (iii)

                          <font size = 4><font color = red><b>6 = a + b + c</font></font></b> ------ eq (i)
                          <font size = 4><font color = red><b>2 = a - b + c</font></font></b> ------ eq (ii)
                         <font size = 4><font color = red><b>34 = 9a + 3b + c</font></font></b> --- eq (iii)

                          <font size = 4><font color = red><b>4 = 2b</font></font></b> ---- Subtracting eq (ii) from eq (i)
                         {{{matrix(2,3, 4/2, "=", b, highlight(2), "=", highlight(b))}}}

                         <font size = 4><font color = red><b>32 = 8a + 4b</font></font></b> ----- Subtracting eq (ii) from eq (iii) ---- eq (iv)
                         <font size = 4><font color = red><b>32 = 8a + 4(2)</font></font></b> --- Substituting 2 for b in eq (iv)
                      {{{matrix(4,3, 32 - 8, "=", 8a, 24, "=", 8a, 24/8, "=", a, highlight(3), "=", highlight(a))}}}


                          <font size = 4><font color = red><b>6 = 3 + 2 + c</font></font></b> ---- Substituting 3 for a, and 2 for b in eq (i)
                          <font size = 4><font color = red><b>6 = 5 + c</font></font></b> 
                          <font size = 4><font color = red><b>1 = c</font></font></b> 

  Equation of a PARABOLA: <font size = 4><font color = red><b>y = ax<sup>2</sup> + bx + c</font></font></b>
                          <font size = 4><font color = blue><b>y = 3x<sup>2</sup> + 2x + 1</font></font> ------- Substituting 3 for a, 2 for b, and 1 for c</pre>