# anyone know the answers to these?

• Jan 23rd 2008, 04:39 AM
jenko
anyone know the answers to these?
1. A test was carried out on a electrical circuit and the following resaults obtained:

4t1+t2=6
-3t1+5t2=0

the 1s and 2s are lower case dont know how to do it sorry!

solve analytically the above simultaneous equatios and check your answer by plotting their graphs on the same set of axes

2. the area of a rectangle is 25.2m2 (squared) and the width is 3.2 metres shorter than the length. calculate the dimentions of the rectangle.

3. solve by factorising the following equations:
x(squared)-6x+9=0
6x(squared)+x-15=0

if anyone can work these out or help me i would be much app cheers!
• Jan 23rd 2008, 05:13 AM
janvdl
Quote:

Originally Posted by jenko
1. A test was carried out on a electrical circuit and the following resaults obtained:

4t1+t2=6
-3t1+5t2=0
by plotting their graphs on the same set of axes

Let $\displaystyle t_{1} = x$ and $\displaystyle t_{2} = y$ and then draw a graph using it as the $\displaystyle y = mx + c$ formula

Quote:

Originally Posted by jenko

2. the area of a rectangle is 25.2m2 (squared) and the width is 3.2 metres shorter than the length. calculate the dimentions of the rectangle.

$\displaystyle L \times W = A$

$\displaystyle A = 25,2 m^2$

$\displaystyle L = x \ metres$

$\displaystyle W = (x - 3,2) \ metres$

So we know that $\displaystyle (x)(x - 3,2) = 25,2$

Quote:

Originally Posted by jenko

3. solve by factorising the following equations:
x(squared)-6x+9=0
6x(squared)+x-15=0

$\displaystyle x^2 - 6x + 9 = 0$

$\displaystyle (x - 3)(x - 3) = 0$

$\displaystyle (x - 3)^2 = 0$

---

$\displaystyle 6x^2 + x - 15 = 0$

$\displaystyle (3x + 5)(2x - 3) = 0$

You can solve them.
• Jan 23rd 2008, 05:47 AM
jenko
are these the answers or formulas?
• Jan 23rd 2008, 05:48 AM
janvdl
Quote:

Originally Posted by jenko
are these the answers or formulas?

These are basically answers. You just have to finish them off.
• Jan 23rd 2008, 07:18 AM
jenko
what are the final answers ive worked them out i need to check them now
• Jan 23rd 2008, 08:37 AM
janvdl
Quote:

Originally Posted by jenko
what are the final answers ive worked them out i need to check them now

• Jan 23rd 2008, 08:43 AM
jenko
i found the length and width of the square but i did not to do it the way of the question but heres what i got

Area=LxW
4.675x5.390= 25.19 is this the correct answer ? but how do i work it out as the question asked?:confused:
• Jan 23rd 2008, 08:45 AM
janvdl
Quote:

Originally Posted by jenko
i found the length and width of the square but i did not to do it the way of the question but heres what i got

Area=LxW
4.675x5.390= 25.19 is this the correct answer ? but how do i work it out as the question asked?:confused:

You have to expand L x W and you have to take the Area over to the left side, to get the right side equal to 0. Then solve.
• Jan 23rd 2008, 08:48 AM
jenko
sorry completely confused can you give me an example using different numbers? tha i can work off? for the questions above? cheers
• Jan 23rd 2008, 08:54 AM
janvdl
Quote:

Originally Posted by janvdl
$\displaystyle L \times W = A$

$\displaystyle A = 25,2 m^2$

$\displaystyle L = x \ metres$

$\displaystyle W = (x - 3,2) \ metres$

So we know that $\displaystyle (x)(x - 3,2) = 25,2$

I am quite certain you know how to use the quadratic formula.

$\displaystyle x^2 - 3,2x = 25,2$

$\displaystyle x^2 - 3,2x - 25,2 = 0$

Now use the quadratic formula to solve for $\displaystyle x$. It's that simple. ;)
• Jan 23rd 2008, 09:02 AM
jenko
no i dont this has just completly confused me ! i realy havent a clue for these ive looked at my notes and i couldnt find anything :S i need each question broken dwn induvadually so do these i cannot find any notes on these in my books from previous lessons these re only practice questions ready for my summer exam it jus the fact that im trying to get these into my head with out using notes as my exams are not open book (allowed to look at notes whilst in exam)
• Jan 23rd 2008, 09:06 AM
janvdl
Quote:

Originally Posted by jenko
no i dont this has just completly confused me ! i realy havent a clue for these ive looked at my notes and i couldnt find anything :S i need each question broken dwn induvadually so do these i cannot find any notes on these in my books from previous lessons these re only practice questions ready for my summer exam it jus the fact that im trying to get these into my head with out using notes as my exams are not open book (allowed to look at notes whilst in exam)
$\displaystyle x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$
$\displaystyle ax^2 + bx + c = 0$