The parabola y = ax^2 + bx + c is graphed below. Find a + b + c. (The grid lines are one unit apart.)
The parabola passes through (-2,8), (0,0), and (2,8).
First, notice that $c$ must be equal to $0$ because when you plug in $(0,0)$ in, you get $c=0$. That way, we only have to solve for $2$ variables.
Now we can plug in the rest of the points, and we get the equations $8=4a-2b$ and $8=4a+2b$.
We can set the equations equal to each other and then we get $b=0$ as well.
Plugging $b=0$ into the equations, we get $a=2$. So $a+b+c$ is $2+0+0$ which is $2$
First, notice that $c$ must be equal to $0$ because when you plug in $(0,0)$ in, you get $c=0$. That way, we only have to solve for $2$ variables.
Now we can plug in the rest of the points, and we get the equations $8=4a-2b$ and $8=4a+2b$.
We can set the equations equal to each other and then we get $b=0$ as well.
Plugging $b=0$ into the equations, we get $a=2$. So $a+b+c$ is $2+0+0$ which is $2$