# [IGCSE] Need help with maths questionWatch

Announcements
#1
Hey there,
I am having troubles with question 12 (last question) in this PDF file.
The question is (if you cannot view the file):
The graph of y=f(x) where f(x)= ax^2 + bx + 3 crosses the x-axis at (-3,0) and (1,0). The y coordinate of the vertex is 4.

a) On the axes sketch the graph for y = f(x)
b) Find the values of a and b
c) Write down the range of f(x) when the domain is R.

A.T.
0
6 years ago
#2
(Original post by Atham)
Hey there,
I am having troubles with question 12 (last question) in this PDF file.
The question is (if you cannot view the file):
The graph of y=f(x) where f(x)= ax^2 + bx + 3 crosses the x-axis at (-3,0) and (1,0). The y coordinate of the vertex is 4.

a) On the axes sketch the graph for y = f(x)
b) Find the values of a and b
c) Write down the range of f(x) when the domain is R.

A.T.
Which part are you struggling with

What have you tried
0
#3
All 3 as I don't know (remember) how to get a,b.
0
6 years ago
#4
(Original post by Atham)
All 3 as I don't know (remember) how to get a,b.
Put in the values for the 2 points that you have

Solve the simultaneous equations
0
#5
What about the vertex point? Is that to help me draw the graph?

EDIT: Okay, I did that. I have a = -1, b = -2. Makes sense now. I was thinking about y = (x-h)^2 +k and all that stuff

0
6 years ago
#6
(Original post by Atham)

I would complete the square for that
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Cardiff Metropolitan University
Sat, 19 Oct '19
• Coventry University
Sat, 19 Oct '19
• University of Birmingham
Sat, 19 Oct '19

### Poll

Join the discussion

#### Why wouldn't you turn to teachers if you were being bullied?

They might tell my parents (26)
7.22%
They might tell the bully (34)
9.44%
I don't think they'd understand (55)
15.28%
It might lead to more bullying (139)
38.61%
There's nothing they could do (106)
29.44%