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# Most annoying maths questions watch

1. Here how I did and never get it correct...

h(x) = 3x - 2
h(x + 1)

x + 1 = 3x - 2
(-1) (-1)

x = 3x - 3 it says 3x - 1 is the answer...

--------------------------------------------------------------------------

f(x) = x^2 + 5x - 1
f(3x)

3x = x^2 +5x -1
the answer was 9x^2 + 15x - 1 and I can't get my head around this one at all.

Does anyone understand these questions and help me out? Thanks.
2. You're not meant to solve an equation like that, wherever x is you instead put x + 1 in the first case and in the second case wherever x is you instead put 3x
3. Hi there, could you write out exactly what the question is?
4. (Original post by ckfeister)
Here how I did and never get it correct...

h(x) = 3x - 2
h(x + 1)

x + 1 = 3x - 2
(-1) (-1)

x = 3x - 3 it says 3x - 1 is the answer...

--------------------------------------------------------------------------

f(x) = x^2 + 5x - 1
f(3x)

3x = x^2 +5x -1
the answer was 9x^2 + 15x - 1 and I can't get my head around this one at all.

Does anyone understand these questions and help me out? Thanks.
Can you post a picture of the question? Thanks.
5. (Original post by Ollie231213)
Hi there, could you write out exactly what the question is?
(Original post by Hydeman)
Can you post a picture of the question? Thanks.
First question.
h(x) = 3x - 2

Work out expressions, giving answers in the simplest form.
ii) h(x+1)

Second question.
f(x) = x^2 + 5x - 1

Work out expressions, giving answers in simplest form.
i) f(3x)

Topic* is function notation.
6. Replace any x with what's in the bracket.

(Original post by ckfeister)
First question.
h(x) = 3x - 2

Work out expressions, giving answers in the simplest form.
ii) h(x+1)

Second question.
f(x) = x^2 + 5x - 1

Work out expressions, giving answers in simplest form.
i) f(3x)

Topic* is function notation.
Replace any x with what's in the bracket.
7. (Original post by ckfeister)
First question.
h(x) = 3x - 2

Work out expressions, giving answers in the simplest form.
ii) h(x+1)

Second question.
f(x) = x^2 + 5x - 1

Work out expressions, giving answers in simplest form.
i) f(3x)

Topic* is function notation.
Like a number machine, "f(x)" and "h(x)" are functions with an input of whatever is in the bracket.

So if h(x) = 3x - 2, it means take whatever x is, multiply by three, and subtract two.

If the input is "x+1", however, it means add one to x first, then multiply by three, then subtract two.

So h(x+1) = 3(x+1) -2
= 3x +3 -2
= 3x +1
8. (Original post by Ollie231213)
Like a number machine, "f(x)" and "h(x)" are functions with an input of whatever is in the bracket.

So if h(x) = 3x - 2, it means take whatever x is, multiply by three, and subtract two.

If the input is "x+1", however, it means add one to x first, then multiply by three, then subtract two.

So h(x+1) = 3(x+1) -2
= 3x +3 -2
= 3x +1
Oh now I get it, thanks.

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Updated: February 1, 2016
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