Express
$$\frac{5(x - 3)}{(2x - 11)(4 - 3x)}$$
in the form
$$\frac{A}{(2x - 11)} + \frac{B}{(4 - 3x)}$$
where A and B are integers. - AQA - A-Level Maths Mechanics - Question 5 - 2021 - Paper 2
Question 5
Express
$$\frac{5(x - 3)}{(2x - 11)(4 - 3x)}$$
in the form
$$\frac{A}{(2x - 11)} + \frac{B}{(4 - 3x)}$$
where A and B are integers.
Worked Solution & Example Answer:Express
$$\frac{5(x - 3)}{(2x - 11)(4 - 3x)}$$
in the form
$$\frac{A}{(2x - 11)} + \frac{B}{(4 - 3x)}$$
where A and B are integers. - AQA - A-Level Maths Mechanics - Question 5 - 2021 - Paper 2
Step 1
Form the identity/equation
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Answer
To express (2x−11)(4−3x)5(x−3) in the required form, we write:
5(x−3)≡A(4−3x)+B(2x−11).
Step 2
Obtain A = -1
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Answer
To find A and B, we can select an appropriate value for x. Let's substitute x=34 into the equation:
5(34−3)≡A(4−3⋅34)+B(2⋅34−11).
This simplifies to (5(-\frac{5}{3}) \equiv A(0) + B(-\frac{5}{3})$$ which gives us A = -1 after solving for it.
Step 3
Obtain B = 1
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Answer
Next, let's substitute x=211 into the original equation:
5(211−3)≡A(4−3⋅211)+B(2⋅211−11).
After simplification, we find that A = -1 leads to B = 1 after appropriate calculations.