Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Find $a$, $b$ and $c$ so the line $y=x$ can be a tangent of the parabola $y=ax^2+ bx+c$ at the point $x=1$. The parabola passes from the point $M(-1;0)$. So I formed the system $$2a+b=1$$ $$a-b+c=0$$ How do I solve this system?

Details : From $y=x$ we see that $k=1$ (we also have that $x=1$) so $2\cdot a\cdot 1+b\cdot 1=1$

share|improve this question
    
@froggie: Is my answer below wrong? :( –  Babak S. Dec 1 '12 at 10:02
    
Wasn't my answer good? :) –  Babak S. Dec 18 '12 at 14:01

1 Answer 1

The parabola and the line intersect each other at $x=1$. This gives you another equation.

share|improve this answer
    
Right! I missed that,thanks :) –  egdfd Nov 29 '12 at 15:27
    
+ Hi, Babak! Hope to see you soon! ;-) –  amWhy Apr 16 '13 at 16:16

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.