Maths Olympiad Prep

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Algebra Difficulty 2.6 Junior Find the answer

The line with equation y=2x6y=2x-6 is translated upwards by 4 units. What is the xx-intercept of the resulting line?

A number or a short expression. Spacing and $ signs are ignored.

Solution

The line with equation y=2x6y=2 x-6 has slope 2. When this line is translated, the slope does not change. The line with equation y=2x6y=2 x-6 has yy-intercept -6. When this line is translated upwards by 4 units, its yy-intercept is translated upwards by 4 units and so becomes -2. This means that the new line has equation y=2x2y=2 x-2. To find its xx-intercept, we set y=0y=0 to obtain 0=2x20=2 x-2 and so 2x=22 x=2 or x=1x=1. Thus, the xx-intercept is 1.

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