# Thread: A few problems I can't work out!

1. ## A few problems I can't work out!

q/t=q/p+1 Express p in terms of q & t
(I'm using / as a fraction thing)

Solve 2 over x-1 minus 3 over x+1 equals 1 over 15

(12-2x)(10-2x)=80
Find the value of x

Thanks for any help, I'll probably need more

2. ## Re :

(1) $\frac{q}{t}=\frac{q}{p}+1$
$\frac{q}{t}-1=\frac{q}{p}$
finally i get $p=\frac{qt}{q-t}$

(2) $\frac{2}{x-1}-\frac{3}{x+1}=\frac{1}{15}$
Try equating the denominator first
$\frac{2(x+1)-3(x-1)}{(x-1)(x+1)}=\frac{1}{15}$
After that cross multiply and solve for x ..

(3) $(12-2x)(10-2x)=80$
some expansion is required here
$120-24x-20x+4x^2-80=0$
Can u continue from here ?

3. Thanks very much. Is it a quadratic equation I need to work out for the last one?

(1) $\frac{q}{t}=\frac{q}{p}+1$
$\frac{q}{t}-1=\frac{q}{p}$
finally i get $p=\frac{qt}{q-t}$
Em where does the -1 go?

5. ## Re :

Originally Posted by 1488ID
Thanks very much. Is it a quadratic equation I need to work out for the last one?

Yes .

6. ## Re :

Originally Posted by 1488ID
Em where does the -1 go?

note that $\frac{q}{t}-1=\frac{q-t}{t}$

note that $\frac{q}{t}-1=\frac{q-t}{t}$
What mathsaddict has done is made 1 into $\frac{t}{t}$ and then solved from there

8. 2 - 3 =
x-1 x+1

cross multiplying

2(x+1) – 3(x-1) = 1
(x-1)(x+1) 15

15(5-x) = x2 – 1
X2 + 15x- 76=0
Factorising
X2+4x+19x-76=0
Becomes
X(x+4)-19(x+4) = 0
Therefore x= -4 and 19

9. Originally Posted by correct
2 - 3 =
x-1 x+1

cross multiplying

2(x+1) – 3(x-1) = 1
(x-1)(x+1) 15

15(5-x) = x2 – 1
X2 + 15x- 76=0
Factorising
X2+4x+19x-76=0
Becomes
X(x+4)-19(x+4) = 0
Therefore x= -4 and 19

Correct