Hey, Could you please explain #35 (practice test 8),thankyou!

Hey,
Could you please explain #35 (practice test 8),thankyou!

The easiest way to go here, assuming you have a calculator that can graph, is to graph both functions and find an intersection.

But that’s not the only way! The algebra is not so bad either. Just set the functions equal to each other and solve!

$-\dfrac{1}{2}(x-4)^2+10=-x+10\\\\-\dfrac{1}{2}(x^2-8x+16)+10=-x+10\\\\-\dfrac{1}{2}(x^2-8x+16)=-x\\\\x^2-8x+16=2x\\\\x^2-10x+16=0\\\\(x-8)(x-2)=0$

From that you know that the solutions are $x=2$ and $x=8$ . Just pick whichever one you like better and grid it in!

PWN Test Prep