How do you find the value of the discriminant and state the type of solutions given 8b^2-6n+3=5b^2?

1 Answer
Jan 31, 2017

Assumption: The only variable is n

Explanation:

color(blue)("Determine the discriminant")

Taken as: 8n^2-6n+3=5n^2

Subtract 5n^2 from both sides

color(red)(3n^2-6n+3=0) larr" Use this one"

Compare to y=ax^2+bx+c = 0

Where x=(-b+-sqrt(b^2-4ac))/(2a)

In your case x is n

The discriminant part is the b^2-4ac giving

(-6)^2-4(3)(3) = 36-36=0

So the discriminant is 0
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color(blue)("Further comments")

color(red)("IF") the graph crosses the x-axis in two different places the quadratic formula results in a solution of format:

"some value " +-" some other value"

However, if the discriminant is 0 as in this case you have:

"some value " +-" "0

giving a single value solution. Consequently the x-axis behave like a tangent to the curve at the min/max point.

So the curve does not actually cross the axis but it more like the two coincide.

However; some people argue that their is always 2 solution but the condition we have hear has the sate of 'duality'.

I am guessing this means that the two solutions happen to coincide thus look as though there is one. This is higher maths 'stuff'.