Chapter 9 - Section 9.1 - Solving Systems of Linear Equations in Three Variables and Problem Solving - Exercise Set - Page 642: 61

$(3, 4, -1)$

$y=ax^2+bx+c$ $(-1, -2)$, $(0, -1)$, $(1,6)$ $x=-1$ $y=ax^2+bx+c$ $-2=a*(-1)^2+b(-1)+c$ $-2=a-b+c$ $x=0$ $y=ax^2+bx+c$ $-1=a*0^2+b*0+c$ $-1=a*0+b*0+c$ $-1=c$ $x=1$ $y=ax^2+bx+c$ $6=a*1^2+b*1+c$ $6=a+b+c$ $a-b+c=-2$ $-1=c$ $a+b+c=6$ $a-b+c=-2$ $a-b-1=-2$ $a-b=-1$ $a+b+c=6$ $a+b-1=6$ $a+b=7$ $a+b+a-b=7-1$ $2a=6$ $2a/2=6/2$ $a=3$ $a-b=-1$ $3-b=-1$ $4-b=0$ $b=4$