slope question

[mrunalum]

on page 190 12th edition question 9
[Deleted because this question is from a banned source - see below.]
bit confused

[supratims]

Is the answer -1 ? If yes, then here is the solution how.

Try to get the equation of the line.
Equation of a line is : y=mx + c.
Also we know, m , the slope = (diff in y coordinates)/(diff in x coordinates)
so, m= (1-2)/(1-1/2) = -2
So line is y=-2x + c
now, find c,
put x=1/2, y=2, we get c = 3.
So line is y = -2x + 3.

Finally put x = 2, and we get y = -1.

[sd]

Even I got the answer as -1. But not sure why this information is given - "line is symmetric with respect to x=2 vertical line". Is this information extraneous then?

Please post the OA and the source.

[sharok50]

Is the answer -1 ? If yes, then here is the solution how.

Try to get the equation of the line.
Equation of a line is : y=mx + c.
Also we know, m , the slope = (diff in y coordinates)/(diff in x coordinates)
so, m= (1-2)/(1-1/2) = -2
So line is y=-2x + c
now, find c,
put x=1/2, y=2, we get c = 3.
So line is y = -2x + 3.

Finally put x = 2, and we get y = -1.

isn't it a parabola question?.if so ,should not we use the y=ax^2+bx+c as equation of the parabola?

[Kweku.Amoako]

could be a parabola x^2 but could also be a cubed function x^3 ..question does not state if linear or not .....we do know it is a decreasing function until the point where x = 2 when it becomes an increasing function. We also know the point x= 2 has the lowest value of y. thats all we know. If we assume x is non-linear we can not solve because we will have more than 3 variables with only 2 equations. The fact that the question is asking a for a value makes it valid to assume it is linear

[Ben Ku]

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