Maths problem

pixeldesign

Can anyone tel me how to find the values of x please . I think its a stupid question but...

Joseph

Well you'd want to change the sign of the bottom and multiply by it 1/1 to get rid of the fraction then just work out whatever you're left with no?

pixeldesign

I did that and i get wrong results....the values of x should be -1 and 5 ..

Richard Cranium

Firstly I'm going to assume that the question should read -3x^2 and not -3^(2)x (which would just be -9x)

If you cross multiply, the denominator is multiplied by 0 anyway, so you need not bother with that (unless my sickness addled mind has forgotten basic algebra).

You'll be left with 3x^2 - 4x + 5 = 0, which is just a normal quadratic equation. Use the formula that's probably in your notes and/or book if you can't factorise it

EDIT: It appears to be a complex numbers question, or else I really have forgotten how maths works. Either way it's just too much for me to handle right now I'm afraid. I'll just go back to bed...

ironclaw

Check the problem. Even solving the top gives a fairly serious complex number answer.

You could multiple across by the bottom but that makes no sense as you remove it, fairly pointless.

jumpguy

Jesus...that's an overly-difficult and confusing question if I've seen one. I thought the first step would be to square out the bottom but it leaves a complication as if doesn't divide into the top line to cancel anything.

I'd need a pin and paper to properly go at it. Make sure that you gave us the question right. Where did you get that question (what book, page number?)

Making It Bad

jumpguy wrote: »

Jesus...that's an overly-difficult and confusing question if I've seen one. I thought the first step would be to square out the bottom but it leaves a complication as if doesn't divide into the top line to cancel anything.

I'd need a pin and paper to properly go at it. Make sure that you gave us the question right. Where did you get that question (what book, page number?)

The first step is to multiply both sides by (2-x)² , this makes the equation -3x²+4x-5=0 , you then multiply both sides by -1 leaving 3x²-4x+5=0 substitute this into the "-b" formula and you should come out with two values for x.

pathway33

Making It Bad wrote: »

The first step is to multiply both sides by (2-x)² , this makes the equation -3x²+4x-5=0 , you then multiply both sides by -1 leaving 3x²-4x+5=0 substitute this into the "-b" formula and you should come out with two values for x.

but the OP said the values for x are -1 and 5

-3(+1) + 4(-1) - 5 = 0 is false

-3(125) + 4(5) - 5 = 0 is false

somethins not right with the question i fear

jumpguy

Making It Bad wrote: »

The first step is to multiply both sides by (2-x)² , this makes the equation -3x²+4x-5=0 , you then multiply both sides by -1 leaving 3x²-4x+5=0 substitute this into the "-b" formula and you should come out with two values for x.

That'd be logical but I've never seen a complex fraction asked where the bottom line can be gotten rid of so easily. As the poster above said, the question must be wrong

pixeldesign

Sorry about that guys.Its my fault...I gave you the wrong result.Check the question from the attached photo.What i did is, i used the Quotient Rule to find dy divide by dx ...but i got a wrong result..

Delta Kilo

This isn't difficult.

As you said, use the quotient rule, this leaves you with -(x^2 +4x+5) over (2-x)^2. The bottom line is irrelevant as it vanishes when you cross multiply as the problem is equal to zero.

Now on top you have -(x-1)(x+5)=0. You can multiply in the minus now leaving you with (x+1)(x-5)=0, therefore x=-1, x=5

pixeldesign

How did you get -(x-1)(x+5)=0 ?

Delta Kilo

pixeldesign wrote: »

How did you get -(x-1)(x+5)=0 ?

I solved the quadratic equation; (x^2+4x+5). I could have multiplied in the minus before I solved it, it doesn't make a difference.