Stuck on a sample question HNC ELECTRICAL (Fractional negative indicies)

[Davey1988]

hi can anyone help me here....

im currently learning with teeside at a distance learning course so im learning on my own.

I current come across a question that is a bit of a nightmare to work out.

here it is:

Write the following in index form (i.e. without roots)






i got 3x^5/2 i dont understand the last bit its calculated. 7/2? where did the 7 come from.

 

[Darkwood]

2+3/2 = 7/2

The whole value 2 is equivalent to 4/2 (four halves)
+ you already have 3/2 so 4/2+3/2 = 7/2

PS the front whole value 2 is not part of a fraction so you have to convert it first before adding to 3/2

 

[Davey1988]

so are you saying if reverse the square root you get fractions in the measurement of "halfs" or is this just because its square root of 2.

...__
4/2

the above will be a result in quaters? which will be 2^1/4

 

[Darkwood]

(2+3/2)

Note the 3/2 is a fraction already
Note the 2 at the beginning is an whole integer

as we have 3/2 this is also the same as three halves + to convert the whole integer 2 to halves it will become 4/2 or four halves.

4/2 + 3/2 = 7/2 or can be expressed as three an a half if you simplified or 3.5

Your getting confused somewhere and overthinking it ... this part of the sum has no roots in it and is basic level fractions.

Look at your sum especially the (2+3/2) ... I think you confusion lies within this bit because the whole number 2 at the beginning is written poorly and appears as the same size physically as the numerator 3 of the fraction so you are reading it as (2/2 + 3/2) where the rest of the sum the whole numbers are larger than the fraction numbers.

 

[Davey1988]

thanks for your help fella, i have another wierd one...



Same with this question can i get any help on this one? once they divide a^2 and b^2 / 4...... they say they get 1/4. how is this?

 

[Davey1988]

or do they just put a 1 above the 4 to make it seprate to a2 & b2. Can you do this?

 

[Richard Burns]

Having (a²+b²)/4 is the same as 0.25 * (a²+b²) or ¼ (a²+b²)

i.e. dividing by four is the same as multiplying by a quarter.

in either case you end up with one fourth of the initial value it is just a different notation to describe the same operation.

You could spread it out and say I am dividing (a²+b²) by four so this is
((a²+b²) /1 ) * (1/4 )

to recombine multiply the tops of the fractions and the bottoms of the fractions
i.e. tops: (a²+b²) * 1
bottoms : 1 * 4

giving (a²+b²) /4

 

[Darkwood]

What he said ^^^^ saves me typing