# Help with transposition

• Oct 4th 2010, 04:40 PM
boomstick777
Help with transposition
Hi, have just started a foundation degree, am doing A level algebra as part of the course, it is all new to me (Shake). Please could somebody help me with the following questions. I need the method for solving these? Any help would be appreciated. See pic below, thankyou

http://i51.tinypic.com/2mnj3uf.jpg
• Oct 4th 2010, 04:42 PM
pickslides
What are your attempts at these?

Have you herd the expression "Inverse operations"?
• Oct 4th 2010, 04:54 PM
boomstick777
Im trying to just get the method of the first one so I can do the rest, k = b^2/a? if I move the sqr'B' to the other side does it become b^2?
• Oct 4th 2010, 05:01 PM
pickslides
This is a novel approach although I don't think the method from the 1st question here could match the other questions. You need to know about using inverse operations and which to apply when.

Making k the subject you need to move it into the numerator.

$\displaystyle a = \frac{\sqrt{b}}{k}$

As it is being divided in the RHS we need to multiply (the inverse of divide) to both sides giving

$\displaystyle a \times k= \frac{\sqrt{b}}{k}\times k$

$\displaystyle a \times k= \sqrt{b}$

Now the only thing keep k from being isolated is the a. It is multiplying so we need to divide it from both sides giving

$\displaystyle a \times k \div a= \sqrt{b}\div a$

$\displaystyle k= \frac{\sqrt{b}}{a}$
• Oct 4th 2010, 05:19 PM
boomstick777
Thankyou! That really helped. There are more complicated questions later on in the assignment any help with the method is much appreciated, will try and do the rest of these ones tommorow, i'll post my answers here and see if they are and good. Thanks
• Oct 4th 2010, 05:20 PM
pickslides
Quote:

Originally Posted by boomstick777
i'll post my answers here and see if they are and good.

Happy to review.
• Oct 5th 2010, 02:36 AM
boomstick777
Is this the correct answer for question 'b'

b = k/a + 2

I used this method
a = sqr(b)/k + 2
a x
sqr(b) = sqr(b)/k + 2 xsqr(b)
a x b = k + 2
a x b/a = k/a +2

Answer - b = k/a +2
• Oct 5th 2010, 12:45 PM
pickslides
Quote:

Originally Posted by boomstick777
Is this the correct answer for question 'b'

b = k/a + 2

I used this method
a = sqr(b)/k + 2
a x
sqr(b) = sqr(b)/k + 2 xsqr(b)
a x b = k + 2
a x b/a = k/a +2

Answer - b = k/a +2

I don't agree with your answer. I'm not exactly sure what you have done!

I get

$\displaystyle a =\frac{\sqrt{b}}{k}+2$

taking 2 from both sides

$\displaystyle a-2 =\frac{\sqrt{b}}{k}$

multiplying both sides by k

$\displaystyle k(a-2) =\sqrt{b}$

and squaring both sides

$\displaystyle k^2(a-2)^2 =b$

$\displaystyle b=k^2(a-2)^2$