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dan18
what is C so that y=2x+3 is tangent to the curve y+x^2 +C?
i think that's y=x^2 +C, right ?
if yes, first take y1=y2, we get a quadratic equation and then to find value of c, take D=0 (D=discriminant) solve for c?
yes, thats what I was thinking, do they mean y=x^2 +C
y=2x+3...........i y=x^2+C........ii
Now, substitute eqn i in eqn ii and tell me what u get
If you want to see the calculation look at the attached file.
thank you very much guys for the help! can I ask why is the D=0 (D=discriminant)?
descriminant is 0 because it is a tangent to the curve, when the descriminant is 0 it has a repeated root, so it just touches the curve, if it were to be greater than 0 it would have two roots which means it would no longer be a tangent, if it were less than 0 it would have two complex roots, not being a tangent,