School/Uni Help Thread

Wondering if anyone can help me! Probably a simple question but I dont have a clue what to do haha

Find the value of 'a' such that k(a)=2h(a)-15

Anyone know? lol Thanks.

 

is that the full question mate?

 

Honestly so confused I dont know if its part of the question before or what!!

The question before was finding h(x) = f(g(x)) and k(x) = g(f(x)): I worked out that k(x) = 4x^2-12x+11 and h(x) = 2x^2+1

Not sure if thats much of a help?

 

don't have a scooby doo mate sorry

 

Haha no problem mate, I probably haven't explained it right either but its only worth 2 marks so its all good

Cheers anyway!

 

Is it higher maths? Think you use differentiation to work it out. I'm guessing that's part (b) to a question, use the answer you got in part (a). Would you be able to post the entire question and I'll see if I can work it out

 

Aye mate its higher maths, no way on earth will I be passing this, thats for sure lol.

2. Functions f and g are given by f(x)= 2x-3 and g(x)= x^2+2

ai) Find h(x) where h(x) = f(g(x))
ii. Find k(x) where k(x) = g(f(x))

b. Find the value of 'a' such that k(a) = 2h(a)-15

Thanks a lot

 

I got booted out of Higher maths

 

Been a while but I'll give it a go:

a is simple, just sub in the terms.
ai) h(x) = F(g(x)) = f(x^2 + 2) = 2(x^2 + 2) - 3 = (2x^2 + 4) - 3 = 2x^2 + 1
aii) k(x) = g(f(x)) = g(2x - 3) = (2x - 3)^2 + 2 = 4x^2 - 6x + 9 + 2 = 4x^2 - 12x + 11

b) k(a) = 2h(a) - 15
Use the terms derived above and sub them in:
k(a) = 4a^2 - 12a + 11
h(a) = 2a^2 + 1

4a^2 - 12a + 11 = 2(2a^2 + 1) - 15 (substitute)
4a^2 - 12a + 11 = 4a^2 + 2 - 15 (cancel the squared terms)
-12a = -13 - 11
-12a = - 24
a = 2

 

Thanks a lot mate I got the answer to part ai. but probably the problem I had was I had the wrong answer to part ii. so wasn't getting the right answer for b!! Thanks for taking the time to do it, much appreciated.

 

Sorry mate just saw you replied now. Been a couple of years since I sat higher maths.. and failed :icon_mrgreen:. Glad you got it sorted though

 

That's just showing off

 

good old calculus

 

Anyone know how to get through college without slitting your wrists lol * I hate classroom based learning.

 

I think the answer to (b) is a=2.
Was an small mistake in the calculation of k(x) in (aii) k(x) should be 4x^2 - 12x + 11

 

I'm in college now, and love it. Probably because I finish in summer for uni. But college has been the best days of my life, really hated school. Suppose what you need to get through it is a decent group of mates. The learning bit is a ballache, but it's really good for me, for banter and laughs.

 

Yeah you're right, well spotted. Edited.

You need to square 1st and 2nd terms then multiply and double both terms to
expand the brackets. According to that I forgot to double it.

 

* I hope I stay on, dont want to go to college. Straight to uni hopefully.

 

Im thinking about doing surveying at aberdeen. The entry requirements are
SQA Highe:230 UCAS Tariff points to include 5 subjects with a minimum of 3 Highers and 2 Intermediate 2 B Grades.

What exactly does this mean? 3 highers and 2 int twos? Whats ucas tarif points?

 

UCAS points allocation is perhaps best explained here. Link is how it works in England but I assume it's pretty much if not exactly the same for Scotland also.

http://www.ucas.com/students/ucas_tariff/