Algerbra- practice questions (1 Viewer)

[Julz_05]

hey guys how u's all doin
lets make this a thread for sample algerbra questions
so anyone got any lol?

 

[sNiPeR_24]

A = πr²

78.53 = π x r²

24.997 = r²

r ≈ √24.997 ≈ 4.9997cm (correct to 4 dec. places)

 

[SaHbEeWaH]

try this, just made it up

expand:

-[-(3 - x) - 2(x - x² + 4)] + (-2)(x² - 6) - (x - 13)

now if y = the above function and y = 0
find possible values for x

 

[Trev]

try this, just made it up

expand:

-[-(3 - x) - 2(x - x² + 4)] + (-2)(x² - 6) - (x - 13)

now if y = the above function and y = 0
find possible values for x

Was it just luck this question came out as an integer? Or you actually put all that random crap together so it would work out fine?
-[-(3 - x) - 2(x - x² + 4)] + (-2)(x² - 6) - (x - 13)
y = 0 = 36 - 4x²
x = +/- 3.

 

[SaHbEeWaH]

actually i just chucked in a bunch of crap and the end result was something like 25 - 4x^2... last bracket was - (x - 2), so i thought might as well make it an integer so added 11
and this was for general people to work on -.-

 

[Trev]

actually i just chucked in a bunch of crap and the end result was something like 25 - 4x^2... last bracket was - (x - 2), so i thought might as well make it an integer so added 11
and this was for general people to work on -.-

25 - 4x²; why not give a fraction to work with?

I am a general person.

 

[sNiPeR_24]

25 - 4x²; why not give a fraction to work with?

I am a general person.

Yes, yes, General in the truest sense of the sentence "Mathematics Extension 2" hahaha.

 

[Danni07]

4x=128
x=32

ummm, let me think of one and i'll post it up soon.

 

[SaHbEeWaH]

4x=128
x=32

ummm, let me think of one and i'll post it up soon.

you might want to retry that

 

[Danni07]

Uh yeah... let's just forget I opened my mouth *blushes*

 

[omigodwhenover]

x + x = ?????????

 

[Casmira]

2x

i had to think about that for a minute

 

[...]

x + 2y = 7 - equation (1)
2x + 5 = 10 - equation (2)


work out the values of x and y

sorry, don't know if this is within the scope of general, but if you can muster this question, your algebra skills ain't too shabby

note: i randomly entered those numbers, so you might get funny expressions in terms of y and x

 

[Danni07]

x = 2.5
y = 2.25
I can't remember doing simultaneous equations in general, but I id it in advanced maths in yr 10.

 

[PC]

x + 2y = 7 - equation (1)
2x + 5 = 10 - equation (2)

How about:

x + 2y = 7 ... [1]
2x + 5y = 10 ... [2]

That's a bit more challenging!

Solving simultaneous equations by an algebraic method is outside the General Course, by solving two linear equations by graphing each straight line is certainly part of the course.

Anyway, find the values of x and y now!

 

[...]

hmm

is it?

well what i was trying to show was that;

when given a function(f(x) = y), try to see that for each variable x, there is a variable of y. So for general people who are not familiar or good at algebra, by doing such questions (provided with good guidance and explanation), they can see how basic algebra expression really works, apart from re-arranging formulas around

 

[...]

x + 2y = 7 ... [1]
2x + 5y = 10 ... [2]

That's a bit more challenging!

Let me try to do this step by step;

first of all, treat one equation at a time, so for equation [1]:

x + 2y = 7 //rearranging the equation making a variable as the "centre" of the equation, in this case, we will use x, as x is by itself whereas y is tagged with 2
hence equation [1] now will look like;

x = 7 - 2y


now look at equation [2]
it is in the form of 2x + 5y = 10
we all know from equation [1] that x = 7 - 2y

we will put x = 7 - 2y into equation [2]

so now it will look like this;
2(7 - 2y) + 5y = 10

now that you've got only y in equation [2];
it works out y to be;
14 - 4y + 5y = 10
y = -4

now we know y = -4, we can put that back into either equation [1] or equation [2] to work out x


put y = -4 back into equation [1];

x + 2(-4) = 7
x + (-8) = 7
x = 15

so x = 15, y = -4