Question

can someone help me please ? with graphs?

Answer 1

whats your question?

Answer 2

Choose the equation below that corresponds to the graph shown.

Answer 3

For a parabola: If you have the co-ordinates of the vertex (h,k)
you can use the formula:
\[\Large y=a \left( x-h \right)^2+k\]

Answer 4

the vertex of your graph is \(\large (-2,5)\)... so you get the equation:
\[\Large y=a \left( x+2 \right)^2+5\]

you just need to solve for \(\large a\) now...

Answer 5

how do i do that ?

Answer 6

you can use a second point on the graph ... whose co-ordinates you know

Since this is a multiple choice question... WHAT are your choices?

Answer 7

you can use points \((-1,3)\) or \((0,-3)\)...

Answer 8

using \((x,y)=(0,-3)\)

\[\Large -3=a(0+2)^2+5\]
\[\Large \implies -3=4a+5\]

Answer 9

y = 2x2 + 8x − 3

y = −2x2 + 8x − 3

y = 2x2 − 8x − 3

y = −2x2 − 8x − 3

Answer 10

from the equation I wrote above : \(-3=4a+5\)..... you get \(4a=-8\)

so, a=-2

\[\Large y=-2\left( x+2 \right)^2+5\]\[\Large=-2\left( x^2+4x+4 \right)+5\]\[\Large=-2\ x^2-8x-8 +5\]
\[\Large\color{green}{=-2\ x^2-8x-3}\]

Answer 11

for multiple choice... the best method is elimination...

you can eliminate A and C....
because the co-efficient of \(\large x^2\) has to be negative... because it looks like upside-down u, instead of right-side up