Simplifying Expressions: 1/2 - 4/d

[priscilla98]

Homework Statement

Express in simplest form.
1/2 – 4/d divide by 1/d + 3/2d

Homework Equations

LCF

The Attempt at a Solution

I know the LCD is 2d. But would you multiply this to the equation

 

[danago]

You can multiply it as long as you do it to the numerator and the denominator. i.e.:

$$\frac{\frac{1}{2}-\frac{4}{d}}{\frac{1}{d}+\frac{3}{2d}} \times \frac{2d}{2d}$$

Also, what you have there isn't really an equation. It is only an equation if there is an equals symbol somewhere.

 

[priscilla98]

Okay, but if you multiply the LCD which is 2d would you multiply 2d to 1/2, 4/d, 1/d and 3/2d

If so, i got 2d/4d - 8d/2d divided by 2d/2d^2 + 6d/2d^2, is this right?

 

[danago]

Okay, but if you multiply the LCD which is 2d would you multiply 2d to 1/2, 4/d, 1/d and 3/2d

If so, i got 2d/4d - 8d/2d divided by 2d/2d^2 + 6d/2d^2, is this right?

Yes you do multiply 2d by 1/2, 4/d, 1/d and 3/2d, but I am not quite sure what you have done there. $$\frac{1}{2}\times 2d = d$$
$$\frac{4}{d}\times 2d = 8$$
$$\frac{1}{d}\times 2d = 2$$
$$\frac{3}{2d}\times 2d = 3$$

 

[priscilla98]

Okay, i understand now. The final answer is d - 8/ 5, thanks a lot

 

[danago]

Okay, i understand now. The final answer is d - 8/ 5, thanks a lot

Yes, that is correct

As a side note, you should probably try to pay more attention to use of brackets. d-8/5 could be interpreted as d-(8/5) or as (d-8)/5, which are two completely different expressions.