If the simultaneous equations
$$y= x^{2}-k$$
y=x
have only one solution, find k.

A. -1
B. $$-\frac{ 1 }{ 4 }$$
C. -4
D. $$\frac{ 1 }{ 4 }$$
E. 1

Question

If the simultaneous equations
 $$y= x^{2}-k$$
y=x
have only one solution, find k.

A. -1
B. $$-\frac{ 1 }{ 4 }$$
C. -4
D. $$\frac{ 1 }{ 4 }$$
E. 1

hartnn · Answer

just put y=x in y=x^2-k
what u get ?

anonymous · Answer

x=x^(2)-k
k=x(x-1)

what's the answer?

hartnn · Answer

the equation is x^2 -x-k=0
now u know how to find k if there is only one solution of quadratic equation ?

anonymous · Answer

just sub the answer into the equation? -.-

anonymous · Answer

is it B?

hartnn · Answer

yes, thats a way , but easier would be to equate discrimant to 0
know what discriminant is ?

anonymous · Answer

b^(2)-4ac
(-1)^(2)-4(1)(-k) ?

hartnn · Answer

yes, equate that to 0

hartnn · Answer

1+4k=0
k= ?

anonymous · Answer

-1/4

thank you
and I have many questions, would you kindly help me ?

hartnn · Answer

i will surely try...i am helping 2-3 ppl at a time...

anonymous · Answer

oh...sorry...I think I can ask another ppl...
you are too busy :P

hartnn · Answer

open it as a new question...if not me, some1 will surely help you :)