MYTUTOR SUBJECT ANSWERS

68 views

How do I evaluate composite functions?

Suppose you have 2 functions: f(x) = 3x2, g(x) = log3(x). These are arbitrary, any functions would work. Evaluate f(g(x)): let y = log3(x) ( = g(x) ), then f(g(x)) = f(y) = 3y2 = 3[log3(x)]2.

The part that people tend to find difficult is remembering what it means to apply a function. A simple subsitution makes this much easier. Whilst the above situation makes it seem easy, consider how much more confusing it could be if f(x) = [x7 + 9x5 + e5x + cos(x-1/3)]/[sin(ex/6) + 1729*x], and g(x) was something similarly complicated; a simple substitution can do wonders and will help prevent confusion.

Seb G. 11 Plus Maths tutor, 13 plus  Maths tutor, A Level Maths tutor...

3 months ago

Answered by Seb, an A Level Maths tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist

182 SUBJECT SPECIALISTS

£24 /hr

Sobia K.

Degree: Mathematics (Masters) - Warwick University

Subjects offered: Maths, Spanish+ 1 more

Maths
Spanish
Further Mathematics

“Second year Maths Undergraduate, here to boost your grades!”

£20 /hr

King Him C.

Degree: Computer Science (Masters) - Durham University

Subjects offered: Maths, Chemistry

Maths
Chemistry

“Hello there! I am a Computer Science undergraduate studying at Durham University. I am very enthusiastic about the understanding of scientific concepts and also the core ideas and building blocks of subjects. I have been tutoring duri...”

£22 /hr

Jonathan P.

Degree: Physics (Masters) - Durham University

Subjects offered: Maths, Physics

Maths
Physics

“About Me: I am a Physics student at Durham University. My passion is physics, and by association maths, I will aim to instil asimilar passion in students during my tutorials. I am a highly patient and approachable individual.  I have...”

About the author

£20 /hr

Seb G.

Degree: Mathematics (Masters) - Bath University

Subjects offered: Maths

Maths

“Me: I'm a second year maths student at the University of Bath. I fell in love with maths after a rocky start with the subject, so believe that I can help people regardless of whether they like maths or not.  I've been tutoring maths l...”

MyTutor guarantee

You may also like...

Posts by Seb

How do I differentiate implicitly?

How do I evaluate composite functions?

How do I find the prime factors of a number?

How do I multiply decimal numbers?

Other A Level Maths questions

Two lines have equations r = (1,4,1)+s(-1,2,2) and r = (2,8,2)+t(1,3,5). Show that these lines are skew.

Use integration by parts to find the integral of xsinx, with respect to x

How would you sketch the curve of a graph?

How do I sketch the graph y = (x^2 + 4*x + 2)/(3*x + 1)

View A Level Maths tutors

Cookies:

We use cookies to improve our service. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok