Question

The figure shows the graph of y=ax^(2)+bx+c. Which of the following is true?
A. a>0, c>0 and b^(2)-4ac>0
B. a>0, c>0 and b^(2)-4ac<0
C. a>0, c<0 and b^(2)-4ac<0
D. a<0, c>0 and b^(2)-4ac>0
E. a<0, c<0 and b^(2)-4ac>0

Answer 1

y-intercept is positive or negative ?

Answer 2

+ve

Answer 3

so, from the equation, find y intercept.

Answer 4

u know how, right ?

Answer 5

a>0, c>0 and b^(2)-4ac>0
a>0, c>0 and b^(2)-4ac<0

either one.

Answer 6

I am confusing about the b^(2)-4ac>/<0 ...

Answer 7

y-co-ordinate of vertex is ?

Answer 8

positive or negative ?

Answer 9

+ve

Answer 10

\[\large b^2-4ac\] tells you how the graph intersects the x-axis.

Answer 11

vertex = (-b/2a,(4ac-b^2)/2a)

Answer 12

so 4ac-b^2/2a is positive
so.... ?

Answer 13

A?

Answer 14

?
a is positive
4ac-b^2 / 2a >0
4ac-b^2 >0

Answer 15

if b^2 - 4ac > 0, the graph intersects the x-axis twice.

Answer 16

and yes, that ^

Answer 17

errrr..

Answer 18

if b^2-4ac = 0, the vertex of the graph is ON the x-axis, and
if b^2 - 4ac < 0, the graph does not intersect the x-axis.

Answer 19

confused ?

Answer 20

then is B?

Answer 21

yes, but u should understand how....

Answer 22

b^(2)-4ac=0 vertex on x-axis
b^(2)-4ac<0 don't intersect the x-axis
b^(2)-4ac>0 two points intersect the x-axis

right?

Answer 23

yes. thats what @sirm3d said

Answer 24

thank you both of you :)