The equations above are all in the format y = m x + c , where m = the gradient, or slope.
So, in the first question, y = 4 x + 2 , the gradient would be 4, because 4 is m in this equation (the number before the x ).
The gradient of a line perpendicular to this line is equal to the negative reciprocal of the gradient of the line. A better way to explain it is if m = the gradient of the line and m ′ = the gradient of the perpendicular line then: m ′ = − m 1
So in the first question, the gradient of the perpendicular line is − 4 1 .
The slope of the line given by the equation y = 2 x + 3 is 2 . A line parallel to this one will also have a slope of 2 , while a line perpendicular to it will have a slope of − 2 1 .
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