For the first, plug an x-value into each equation to determine which gives out the y-value.
\(-2.5(-2)^2+5(-2) \)
Simplify.
\(-2.5(4)-10\)
\(-10-10=-20\)
This is the y-value of (-2,-20), so it works. Now plug the x values from the other equations in.
-2.5(0)2+5(0)
Simplify.
-2.5(0)+0
0+0=0
0 is not the y-value of (0,-4), so you have to try another.
\(-(-2)^2+4(-2)-4=-4-8-4=-16\)
This is not the y-value of (-2,-20), so try another.
\(-2(-2)^2+4(-2)-4=-8-8-4=-20\)
This is the y-value of (-2,-20), so it works. Now plug the x values from the other equations in.
\(-2(0)^2+4(0)-4=0+0-4=-4\)
This is the y-value of (0,-4), so plug in the final point.
\(-2(4)^2+4(4)-4=-32+16-4=-16-4=-20\)
This is the y-value of (4,-20), so the equation is -2x2+4x-4.