Question

Where is the vertex of the graph of y equals negative x squared plus 2 x plus 5 located?

(1,5) < it's not this one
(1,6)
(-1,3) <--
(-1,2)

Which values best approximate the solutions of -4x^2+7x+5=0?

0.9 and 2.3
0.9 and 5
-0.5 and 2.3 <--
-0.5 and 5

What is the solution set of 5x2 - 20 = 15x?

{1,-4}
{-2,2}
{-1,4} <--
{-2}

Answer 1

y = -x^2 + 2x + 5

the x of the vertex is -b/(2a) = -2/(-2) = 1
plug in x = -1, y = -1+2+5 = 6
vertex is (1,6)

-4x^2+7x+5=0
4x^2 - 7x - 5 = 0
x = (7 ± √129)/8 = appr (7±11)/8
= appr 18/8 or -4/8 or appr 2.5 or -1/2

your choice is good

5x^2 - 20 = 15x
x^2 - 3x - 4 = 0
(x-4)(x+1) = 0
x = 4 or x = -1

ok

Answer 2

Thank you! :D