Question

Suppose the function shown below was expressed in standard form, y=ax^2+bx+c. What is the value of a?

(will attach graph in a sec!)

A. 2
B. -1
C. 4
D. 1

***Idk how to solve.. :( please explain? thanks :)

Answer 1

how'd u get -1??

Answer 2

sorry,find the roots

Answer 3

how do i do that??

Answer 4

\[x _{1}=0,x _{2}=2\]
and plug this into
\[y=a(x-x _{1})(x-x _{2})\]

Answer 5

so i get this??
y=a(x-0)(x-2) ??
what do i do now?? and was that right?

Answer 6

use an extra point on the graph that is visible

Answer 7

is that point (1,-2) ??

Answer 8

and plug it into the above equation\[y=a(x)(x-2)\]
yes (1,-2)

Answer 9

ok
y=a(1)(1-2)
=a(1)(-1)
=a(-1)
=-a??
so my answer is -1??
my answer is B. -1
????

Answer 10

no thats a trap

Answer 11

ohhh okay :/ so what do i do then??

Answer 12

substitute also on the right ie y=-2

Answer 13

\[-2=a(1)(1-2)\]

Answer 14

ohhh i see so i get this??
-2=a(1)(1-2)
-2=a(1)(-1)
-2=a(-1)
divide both sides by -1??
and i get 2=a
???
so my answer is A. 2
??

Answer 15

yes

Answer 16

whoo hoo!! thanks for clarifying that!! wow, a trap?!! haha thanks @jonask :)

Answer 17

do you get the method

Answer 18

yeah :) thanks!!