Maths help please

W

Wozza63

Biblical Poster
Is anyone here good at maths, got my exam tomorrow and cannot afford to screw this one up, so if i post a few questions and stuff would someone perhaps be able to explain this stuff, thanks, there is lots of rep available as that is the only bribe available

so can anyone solve this and tell me how they got it

Solve this quadratic equation
25x^2-4=0

THANKS, got quite a few i wanna post here, seeing as i would really like an A-Star as its probably the only subject i could get one in
 
Rakk

Rakk

The Awesome
Moderator
25x^2-4=0
25x^2=4
x^2=4/25
x=2/5

:)

Edit: it's been quite a while since I last did quadratic equations, but I think that looks about right :):)
 
Last edited:
Rakk

Rakk

The Awesome
Moderator
Well (5x+2)(5x-2) does indeed =25x^2-4

Not quite sure what else you're looking for though apart from, unless its that (-b+-root(b^2-4ac))/2a thingy that I really haven't used since before you were born :)
But in case it is then a=25, b=0, c=-4
(-0+root(-4x25x-4))/2x25
= root(400)/50
= 20/50
= 2/5
 
Nemesis

Nemesis

Moderator
Moderator
you do both as there are two answers to quadratic equations (at least the ones you will be asked to solve)

every positive number has two square roots ie. V4 = 2 OR -2

also once you get to (5x+2)(5x-2)= 0 for instance one of the brackets must equal 0
so you solve it from there to get
5x+2 = 0
5x = -2
x = (-2)/5
OR
5x-2 = 0
5x = 2
x = 2/5
 
Rakk

Rakk

The Awesome
Moderator
Um, I haven't done quadratic equations in an awful long time, so this is what I reckon having looked at it.
Most quadratic equations have two answers, so the + bit gives one of the answers and the - bit gives you the second answer to the problem.
So the 25x^2-4=0 can be +2/5 or -2/5 (I failed to mention the -2/5 earlier cos I completely forgot about that stuff)
 
Rakk

Rakk

The Awesome
Moderator
Wozza365 said:
yeh i looked at it, although didnt seem much good, revision notes are pretty useless in maths for me it seems, i need to try and do it over and over, and then remember it as well,
Click to expand...
Yeah, when I was doing maths at school, I found this too, using the equations over and over gets it in your head :):)

Wozza365 said:
i would have benefited a lot if i had a good teacher
Click to expand...
Hehe, yeah, I blame my physics teacher entirely for making me think I wouldn't be able to do physics (he basically told us none of us were good enough to do physics at GCSE level when we were choosing GCSE subjects to do, as it happens my second highest score after maths in the exams that year was physics, but it was too late to change my choices at that point), when if I had done I'd probably have got an A at A-level.
 
tom_gr7

tom_gr7

Life Serving
good luck wozza,

I'm afraid I cant help, even though I have equivalent to a A level at maths. No idea how I got that. Only had one good teacher in my life at maths and by that time I was too far behind to learn everything, then the teacher moved on. Was good at maths when younger but due to teachers not taking giving a bean, and not wanting to help me, when I was a teenager I kinda gave up hope of ever being able to learn most of it.

tom
 
Frenchy

Frenchy

Prolific Poster
X^2 = a has two possible values for x, one negative and one positive, this is because if you square a value positive * positive = positive and negative * negative = positive so your second answer in an equation such as yours will always have an answer x and its conterpart -x
 
DeadEyeDuk

DeadEyeDuk

Superhero Level Poster
Rakk said:
Hehe, yeah, I blame my physics teacher entirely for making me think I wouldn't be able to do physics (he basically told us none of us were good enough to do physics at GCSE level when we were choosing GCSE subjects to do, as it happens my second highest score after maths in the exams that year was physics, but it was too late to change my choices at that point), when if I had done I'd probably have got an A at A-level.
Click to expand...

My A Level Maths Statistics teacher got me an overall C! I got an A in Pure Maths (read PROPER maths) and a U in stats! Only one difference between the two...the teacher :D
 
Frenchy

Frenchy

Prolific Poster
lol "PROPER maths".

I love maths, probably my favourite subject, but then I have done A-Level Maths and Further Maths and a degree in Aeronautical engineering lol.
 
C

calduf

Silver Level Poster
Hey, we just recently finished quadratic equations, so I would help the best I can, but I find it quite difficult to interpret what is meant on this by what is typed as its quite different irl, written on paper lol!
 
Frenchy

Frenchy

Prolific Poster
Thats why I do all my word processing in LaTeX :) (No i dont mean I sit around writing in tightly fitted clothes haha). It makes equations look awesome and generally the layout looks great.
 
You must log in or register to reply here.
Top