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# maths question help please? :(

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1. my exam is tomorrow
http://qualifications.pearson.com/co...e_20120516.pdf
can anyone do question 21? i looked at the mark scheme but it doesnt make sense
please explain to me step by step bc i suck at maths
thank u so much

edit: thanks everyone xxxxxxxxxxxxx
2. Times x+2 up to the 9 and times x-2 up to the 5 so everything is on one line. So it'll be 9x+18+5x-10=5 then simplify it and solve!
3. (Original post by gameofno)
my exam is tomorrow
http://qualifications.pearson.com/co...e_20120516.pdf
can anyone do question 21? i looked at the mark scheme but it doesnt make sense
please explain to me step by step bc i suck at maths
thank u so much
Multiply both sides by (x+2)(x-2) and solve the quadratic that you form.
4. good luck.
5. (Original post by gameofno)
my exam is tomorrow
http://qualifications.pearson.com/co...e_20120516.pdf
can anyone do question 21? i looked at the mark scheme but it doesnt make sense
please explain to me step by step bc i suck at maths
thank u so much
So if you have 12 boys and the mean for one boy is 18.
You do 12x18=216

Then you do the same for the 8 girls with the mean of 16.5
So you do 8x16.5=132

Now since the question asks you for the whole group (Boys and Girls) you add the numbers together.
132+216=348

But since you want the mean of the whole group you have to divide by the total amount of people so.. 12 boys+8 girls= 20 students altogether.

Then with both means added together you divide by the total number of students to get the mean of the combined group.

132 (Mean for Girls) + 216 (Mean for Boys) / 20 (Total number of boys plus girls)= 17.4 (Mean of Boys and Girls put together)

Hope this helps!
6. (Original post by gameofno)
my exam is tomorrow
http://qualifications.pearson.com/co...e_20120516.pdf
can anyone do question 21? i looked at the mark scheme but it doesnt make sense
please explain to me step by step bc i suck at maths
thank u so much
ok so first ,
1) you have to multiply the (x+2) by the diagonally opposite number which is 92) so at the top write 9x+18
3) then multiply the (x-2) by its diagonally opposite number which is 5
4) which is 5x-10
5) then ADD that onto the number at the top which is 9x+186) so at the top you now have (9x+18)+(5x-10)
7)which simplifies down to 14x+8
8) then at the bottom , you multiply the two bottom numbers
9) so just write it as (x+2)(x-2)
10) so now u have a fraction on one side and number 2 on the other side
11) now multiplly the bottom part of ur fraction with the 2- so take the (x+2)(x-2) to the other side and multiply it by 2
12) now you have 14x+8 = 2(x+2)(x-2)
13) which simplfies down to 14x+8= 2x^2-8
14) now you have to make this into a quadratic equation which equals 0
15) so take the 8 on the left side over to the right side and make 2x^2-16
16) then take the 14x over to the right side and make 2x^2-14x-16=0
17)now you can see that this equation is divisible by 2 = so u can write it down as x^2-7x-8
18) now all you have to do is factorise this to get the answer you want - im sure u know how to do thatthere will be two Xshope this helps - ik its a bit long x
7. Are the answers 8 and -1?

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