K
K
Karina2016-05-03 00:41:53
Mathematics
Karina, 2016-05-03 00:41:53

How, on the basis of any equality, to understand that one equality is equal to another?

Hello.
I'm trying to take a coursera in mathematics, but apparently I don't understand the most basic things.
There are such tasks:

f(6) = 9
f(x) = g(x) + 2

Question: what points on the graph can we determine on the graph for the function g?
How is it solved:
f(6) = g(6) + 2
f(6) = 9
9 = g(6) + 2
g(6)=7

I don't even understand the first step. The author equates f(6) = g(6) + 2 - why so! nowhere is this in the condition! if it were in the condition g(x) + 2 = 9 , then one could agree. But on the basis of what the author draws such conclusions - I do not understand at all. What is it and where can you read about it?
Thank you all for your help.

Answer the question

In order to leave comments, you need to log in

2 answer(s)
I
index0h, 2016-05-03
@iKapex

x is a variable.
f(6) = 9 - here you know that some operation f on the variable x, in this case equal to 6, gives 9
in the second line, you need to substitute the same number 6 instead of x. But you already know from the first line that f(6 ) = 9
you get 9 = g(6) + 2, from here you find g(6)
----------
You are not required to know how f and g behave. All you can do is check their value for a particular x

D
Daniil Igorevich, 2016-05-03
@Petr_Anisimov

This happened because the author substituted 6 instead of x for the equation f(X)=g(X)+2
f(6) = 9 from the condition, and therefore that
g(6) + 2 = 9 (because f(X ) = g(x) + 2, then it turns out that g(x) + 2 form the desired nine at f(6), but instead of X it will be 6)
g(6)=9 - 2 = 7

Didn't find what you were looking for?

Ask your question

Ask a Question

731 491 924 answers to any question