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Mathematics 18 Online
OpenStudy (waheguru):

Can you explain how to solve this?

OpenStudy (waheguru):

hartnn (hartnn):

what do you do to find the point of intersection ?

OpenStudy (waheguru):

For linear we can use substitution or elimination but im not sure for this

OpenStudy (anonymous):

Try completing the square to get in vertex form?

hartnn (hartnn):

we solve the equations simultaneously. so, here we'll have x^2-6x+14 = -x^2-20x-k and here, 'x' will have a repeated root. this is one of the many ways of solving it...

hartnn (hartnn):

a quadratic equation has repeated root when b^2-4ac = 0

OpenStudy (waheguru):

Yea I understand that when the descriminat is 0 there is one intercept

hartnn (hartnn):

do u need the vertex method to solve this ? or any method will do ?

OpenStudy (waheguru):

hmm, I guess we can try vertex

hartnn (hartnn):

then i would let @phi or @wio continue :)

OpenStudy (waheguru):

what way were you going to shiw?

OpenStudy (waheguru):

I got the vertex form s and I got (x-3)^2+6 and -(x-10)^2-k+100

hartnn (hartnn):

x^2-6x+14 = -x^2-20x-k bring it in the form ax^2+bx+c=0 then use b^2=4ac to find k

OpenStudy (waheguru):

@hartnn can you show that way

OpenStudy (waheguru):

so we want to find when it has one rooot/ but how can we find k like this?\

hartnn (hartnn):

x^2-6x+14 = -x^2-20x-k 2x^2+14x+14+k=0 a=2 b=14 c=14+k b^2=4ac 14^2=4*2*(14+k) easy to find k from here....

hartnn (hartnn):

and wouldn't the vertex form be (x-3)^2+5 and -(x-10)^2-k+100

OpenStudy (waheguru):

How can we set the equations to equal to eachother when they could be repersenting different parabolas that is what is confusing me

hartnn (hartnn):

to find the points of intersection between any 2 curves y=f(x) and y=g(x), we solve them simultaneously, by letting f(x) = g(x), finding values of x and then y.

OpenStudy (anonymous):

You are setting them equal for particular value of \(x\).

ganeshie8 (ganeshie8):

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