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Quadratic eq. and graphs - WAS...
The graph of the curve y = 2x2 - x -1 and a straight line PQ were drawn to solve the equation 2x2 - 5x+2 =0. What is the equation of the line PQ?

Correct Answer

Incorrect Answer

How to get the right answer:

Let the straight line be px+q

According to the question, the solution of the curve 2x2 - 5x+2 = 0 is when y = 2x2 - x - 1 = px+q

2x^2 - x - 1 = px+q

Rearrange this

By comparing this expression to 2x2 - 5x+2 = 0, we can write 

1+p=5 \Rightarrow p=4 and

Therefore the equation of line PQ is