Maths Olympiad Prep

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, 2025

Algebra Difficulty 1.0 Junior Prove it Canada

If $4(x-2) =
2(x-4),whatisthevalueof, what is the value of x$?
If $2x =
9,whatisthevalueof, what is the value of 2^{6x-23}$?
Determine the coordinates of the point of
intersection of the lines with equations $y =
3x + 7and and y = 7x +
3$.

Solution

Since 4(x2)=2(x4)4(x-2) = 2(x-4), then
4x8=2x84x - 8 = 2x - 8 which gives 2x=02x = 0 and so x=0x=0.
Solution 1:

If 2x=92x = 9, then 6x=32x=39=276x = 3 \cdot 2x = 3 \cdot 9 = 27.

This means that $2^{6x-23} = 2^{27 - 23} =
2^4 = 16$.

Solution 2:

If 2x=92x = 9, then x=92x = \frac{9}{2}.

Therefore, $6x - 23 = 6 92\cdot \tfrac{9}{2} -
23 = 27 - 23 = 4$.

Thus, $26x\$2^{6x} - 23} = 2^4 =
16$.
Equating expressions for yy,
we obtain 3x+7=7x+33x + 7 = 7x + 3, which
gives 4=4x4 = 4x and so x=1x = 1.

Since x=1x = 1, then y=3x+7=3+7=10y = 3x + 7 = 3 + 7 = 10, and so the point
of intersection has coordinates $(1,
10)$.

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.