Help with some maths questions please? (Basic Yr 10 q's) (1 Viewer)

[CVS]

Hi

First time here so hope everything's right.

I have an upcoming maths test and I've gone through last year's paper which we got emailed (it includes answers) and completed the test, making a list of questions where I don't understand how to progress to the answer provided.

Let me say I'm at a selective school where everyone else are maths geniuses! But I'm pretty slow at maths, it's my worst and least favourite subject by a very long shot. So the questions I'm stuck on are very basic and some worth only 1 or 2 marks, so I feel like I should be able to "get" them.
There's about 15 questions... but if I can understand 1 or 2 of them, that's a few more marks and very much worth it. The answers are already given so I would really like help in just understanding how to get there.

If anyone could please help me I would greatly appreciate it, and will post a few of the questions.

Kind regards

 

[HSC2014]

Don't be afraid to ask for help; where are the questions?

 

[Smile12345]

I'll help.

 

[CVS]

Hello,

Sorry for the delay, the replies were sent to my junk folder

Anyway can I put the first two, each worth 1 mark and maybe just a good gauge of the level I'm doing?

1. What is the gradient of the line with the equation
2x+3y-7=0
=m = -2/3

2. Find the equation of the axis of symmetry of the parabola with equation
y=(x^2)+6x-9
x=-3
...part b: What is the minimum value of the formula?
y=-18

They're probably not hard at all but I just don't know!

Thank you again for the kind offers

 

[Menomaths]

 

[CVS]

Thank you very, very much! I remember doing that now, so that's extremely helpful

 

[HeroicPandas]

Q2. Axis of symmetry is found by:

x = -b/2a

Quadratic: y = ax^2 + bx + c

So, y=x^2 + 6x - 9

a = 1, b = 6, c = -9

x = -b/2a

x = -6/2(1)

x = -3

Q3.
Method 1: Sub x = -3 into the parabola

Method 2:

y = x^2 + 6x - 9

Complete the square,

y = (x+3)^2 - 18

y + 18 = (x+3)^2

We notice that (because anything squared must be greater or equal to zero)





If y is greater than OR EQUAL TO -18, then y can be -18, -17, -16- 15, -10, -5, 0, 4, 7, 96, 10000000000

So the minimum value of 'y' (the formula) is -18

 

[CVS]

Thank you so much. I'm getting this now, and it always feels good when you're getting something - thanks again!