y= -5
y equals x plus 5 is the equation of a straight line in the x-y plane.
8
Yes. This is a logical deduction based on substitution. if x + y = 7 and y = 5 then the value of 5 can be substituted for y to get x + 5 = 7 which can then be solved to get x = 2, meaning the point (2, 5) is a solution to the line x + y = 7 as it is on that line.
5
If you mean a line of y = 2x+5/4 and a curve of y^2 = 10x Then it works out that the line touches the curve at: (5/8, 5/2)
-8
When the equation of a line is written in standard form: y = mx + c, the slope of the line is m. Here, y = 3x + 5 so slope = 3
7
-1/5
The equation of the line is y = 7x + 5 The gradient = the slope of the line = dy/dx = 7, in this case. The y-intercept is 5. ========================
That line is horizontal on the graph. Its slope is zero.