ATAR Notes: Forum

Uni Stuff => Science => Faculties => Mathematics => Topic started by: TrueLight on November 10, 2009, 09:50:31 pm

Title: Help with simple maths problem! please
Post by: TrueLight on November 10, 2009, 09:50:31 pm: hi

can someone explain to me how to solve this maths equation by hand! thanks... and actually tell me what your doing to...thanks

its really simple but lol shutup

something like

= 120/1*10^-7

and something like

=100/0.2*10^-6

thanks
Title: Re: Help with simple maths problem! please
Post by: TrueTears on November 10, 2009, 09:52:11 pm: $\frac{120}{10^{-7}}$

$= \frac{120}{\frac{1}{10^7}}$

$= 120 \times 10^7$

Other one:

$\frac{100}{0.2 \times 10^{-6}}$

$= \frac{100}{\frac{2}{10} \times \frac{1}{10^6}}$

$= \frac{100}{\frac{2}{10^7}}$

$= 100 \times \frac{10^7}{2}$

$= \frac{10^{9}}{2}$

$= 5 \times 10^8$
Title: Re: Help with simple maths problem! please
Post by: TrueLight on November 10, 2009, 10:26:47 pm: thanks!

can you explain how you got from 100/2/10^7 onwards... and also 120/1/10^7 onwards... thanks
Title: Re: Help with simple maths problem! please
Post by: qshyrn on November 15, 2009, 02:02:45 am: Quote from: TrueLight on November 10, 2009, 10:26:47 pm
thanks!

can you explain how you got from 100/2/10^7 onwards... and also 120/1/10^7 onwards... thanks
when a number divides by a fraction, its the same as multiplying that number by the reciprocal of the fraction (flipping the fraction over)
Title: Re: Help with simple maths problem! please
Post by: TrueLight on November 15, 2009, 10:46:04 am: ah yeah! lol my brain doesn't retain maths for very long

so how does 10^9/2 get to 5*10^8

where did the 10^8 come from?
Title: Re: Help with simple maths problem! please
Post by: m@tty on November 15, 2009, 02:48:15 pm: $\begin{align}\frac{10^9}{2}&=\frac{10^1 \cdot 10^8}{2} \\<br /><br />&=\frac{10}{2} \cdot 10^8 \\<br /><br />&=5 \cdot 10^8 \end{align}$
Title: Re: Help with simple maths problem! please
Post by: TrueLight on November 15, 2009, 05:20:19 pm: oh! duh omg so smart! thanks!