# anyone need help for maths?Watch

Thread starter 4 years ago
#1
Exam tommorow and i'll be glad to help with your revision, so fire away.
0
4 years ago
#2
Concerning graphical transformations...what's the difference between f(2x) and 2f(x) ?????

Posted from TSR Mobile
0
4 years ago
#3
(Original post by chazer154)
Concerning graphical transformations...what's the difference between f(2x) and 2f(x) ?????

Posted from TSR Mobile
2f(x) stretches the graph vertically by twice as much.

f(2x) stretches (or squashes) it by 1/2 horizontally
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Thread starter 4 years ago
#4
(Original post by chazer154)
Concerning graphical transformations...what's the difference between f(2x) and 2f(x) ?????

Posted from TSR Mobile
2f(x) stretches the function twice vertically and f(2x) makes the function smaller horizontally by 0.5
0
4 years ago
#5
i need help with probability
0
4 years ago
#6
I don't understand how to factorise fully - I can only do simple and I can't prove algebraically
0
4 years ago
#7
(Original post by miageogiaxxxx)
i need help with probability
What specifically?

want an example?
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Thread starter 4 years ago
#8
(Original post by Emilythorb)
I don't understand how to factorise fully - I can only do simple and I can't prove algebraically
ok can you factorise 2x squared + 7x + 6?
0
4 years ago
#9
(Original post by aadil10)
What specifically?

want an example?
just in general do not understand like it completely confuseses me
for example: 4 girls , 6 boys in one class, whats the probability teacher choses two boys if he selects two students at random
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4 years ago
#10
(Original post by shwansalah)
ok can you factorise 2x squared + 7x + 6?
Hm I would probably say x ( x + 7 And then I'd be stuck
0
4 years ago
#11
(Original post by miageogiaxxxx)
just in general do not understand like it completely confuseses me
for example: 4 girls , 6 boys in one class, whats the probability teacher choses two boys if he selects two students at random
Okay so first thing about the probabilities of each one just once.

Add them all together first so 4+6=10 students in the class

this means: 4/10 girls 6/10 boys which you can simplify to 2/5 girls 3/5 boys.

So now you want the probability of getting boys and then boys again.

If it's a probability of something and something else you times them together.

So 3/5 times 3/5 = 9/25
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Thread starter 4 years ago
#12
(Original post by Emilythorb)
Hm I would probably say x ( x + 7 And then I'd be stuck
2x squared +7x + 6, ok first you do 2 times by the end number which makes 12

then two numbers times to make 12 and plus to make 7

4 and 3 works,

therefore we substitute it back into the equation

2x squared + 4x + 3x+ 6 ,

we factorise 2x squared + 4x and 3x + 6 seperately,

2x squared + 4x, we can take out a 2x

so

2x(x+2)

3x+6 we can take out a 3 so 3(x+2)

so answer is (2x+3) and (x+2)
0
4 years ago
#13
(Original post by Emilythorb)
Hm I would probably say x ( x + 7 And then I'd be stuck
A number 'squared' is written as 'x^2' btw. (edit: think I managed to do a squared symbol though)

so 2x² + 7x + 6 is a quadratic. This means you will have two brackets with x in. Because it's 2x² you will have 2x in one and x in the other like this:

(2x ) (x )

Then you need to find two numbers with multiply to make the number on the end (6) and add/total to make the number in the middle (7). The best way to do this is to use two factors of the end number (6) and try them out. e.g. 3 and 2.

Because the end number of the equation is positive (2x² + 7x + 6) the two numbers you picked will go into the bracket as positive like this:

(2x + 2) (x + 3)

If you expand this however you get 2x² + 6x + 2x + 6 which is 2x² + 8x + 6.
You have made the 3rd number but not the 2nd.

If you try switching the numbers like this:

(2x + 3) (x + 2)

It expands to 2x² + 4x + 3x + 6 which is 2x² + 7x + 6, the original equation.
So (2x + 3) (x + 2) is the factorised equation.

Hope this made sense 0
4 years ago
#14
(Original post by aadil10)
A number 'squared' is written as 'x^2' btw. (edit: think I managed to do a squared symbol though)

so 2x² + 7x + 6 is a quadratic. This means you will have two brackets with x in. Because it's 2x² you will have 2x in one and x in the other like this:

(2x ) (x )

Then you need to find two numbers with multiply to make the number on the end (6) and add/total to make the number in the middle (7). The best way to do this is to use two factors of the end number (6) and try them out. e.g. 3 and 2.

Because the end number of the equation is positive (2x² + 7x + 6) the two numbers you picked will go into the bracket as positive like this:

(2x + 2) (x + 3)

If you expand this however you get 2x² + 6x + 2x + 6 which is 2x² + 8x + 6.
You have made the 3rd number but not the 2nd.

If you try switching the numbers like this:

(2x + 3) (x + 2)

It expands to 2x² + 4x + 3x + 6 which is 2x² + 7x + 6, the original equation.
So (2x + 3) (x + 2) is the factorised equation.

Hope this made sense I understand all of this but I don't understand how you managed to get it back to 7x??
0
4 years ago
#15
(Original post by Emilythorb)
I understand all of this but I don't understand how you managed to get it back to 7x??
Okay so the factorised equation is (2x + 3) (x + 2)

When you expand it you have to multiply all the left side by all the right side:

2x X x = 2x²

2x X 2 = 4x

3 X x = 3x

3 X 2 = 6

so you have 2x² + 4x + 3x + 6

The '4x + 3x' simplifies to '7x'

so you get 2x² + 7x + 6
0
4 years ago
#16
(Original post by shwansalah)
Exam tommorow and i'll be glad to help with your revision, so fire away.
How do I factorise equations such as 2x^2-7x+3

I know how to regular ones that have a single x^2 but when they're like this with more than one x^2 then I have no idea. Can you link me to some help or explain this for me?
0
Thread starter 4 years ago
#17
2x squared - 7x+3

FIRST, you do the first number times the end number, ( 2 TIMES 3= 6)

SECONDLY, two numbers that times to make 6 and plus to make -7, the answer is -6 and -1

THRIDLY, the expression was 2x squared -7x + 3,

NOW it becomes 2x squared -6x -1x +3 , ( we split the -7x into -6x and -1x)

NOW we factorise each part seperately

so we first factorise 2x squared -6x which is 2x(x-3)

Then we factorise the -1x + 3 which is -1(x-3)

which becomes (2x-1) and (x-3) which is ur final answer
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Thread starter 4 years ago
#18
(Original post by joe4234)
How do I factorise equations such as 2x^2-7x+3

I know how to regular ones that have a single x^2 but when they're like this with more than one x^2 then I have no idea. Can you link me to some help or explain this for me?
Forgot to reply directly to you, woops, anyway the solution is above ^^^^
0
4 years ago
#19
(Original post by aadil10)
Okay so first thing about the probabilities of each one just once.

Add them all together first so 4+6=10 students in the class

this means: 4/10 girls 6/10 boys which you can simplify to 2/5 girls 3/5 boys.

So now you want the probability of getting boys and then boys again.

If it's a probability of something and something else you times them together.

So 3/5 times 3/5 = 9/25
uhmmm sorry, but for this question wouldnt the probability be slightly less than that?

If you don't simplify it, just so it's clearer to see:

so 4/10 girls, and 6/10 boys
P(boy) on the first choice = 6/10
but P(boy) on second choice (assuming a boy was chosen the first time) would be 5/9 as one boy has been picked so cannot be picked again?
So the overall probability would be 5/9 x 6/10, which is 1/3 Sorry if this is over complicating stuff 0
4 years ago
#20
Rearrange this equation?
P=n²+a/n+a -------->>> Rearrange this equation to make a the subject

Help please!! I got a=n^2/pn+p-1 is it correct?
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