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Mathematics 15 Online
OpenStudy (devonhoward15):

Picture inside

OpenStudy (devonhoward15):

OpenStudy (devonhoward15):

@mathmale @mathstudent55 @alivejeremy

OpenStudy (g3n3sis08):

Have you heard about differentiation?

OpenStudy (devonhoward15):

no

OpenStudy (g3n3sis08):

Okay then completing squares?

OpenStudy (devonhoward15):

no

OpenStudy (devonhoward15):

i have 2 common points and vertex below x-axis

OpenStudy (g3n3sis08):

y=-2x^2+x-3 Using completing squares. .Take -2 out of brackets. -2(x^2 -x/2 + 3/2) then, -2[(x-1/4)^2-(1/4)^2 + 3/2 ] -2[(x-1/4)^2-1/16+3/2] -2[(x-1/4)^2-23/16] -2(x-1/4)^2-23/8

OpenStudy (g3n3sis08):

vertex is ( 1/4 , -23/8)

OpenStudy (devonhoward15):

am i right?

OpenStudy (g3n3sis08):

There are no common points because b^2-4ac is < 0. when the discriminant is <0 there are no common points ( 0 roots) when its = 0 there is only one root e.g tangents to a curve when its > 0 there is more than one root y=ax^2+bx+c in this case y=-2x^2+x-3 b is (1)x a is (-2)x^2 c is (-3) so b^2-4ac 1^2 - (4x-2x-3) 1-24 is 23 which is <0 there fore no roots hense no common points.

OpenStudy (devonhoward15):

you sure?

OpenStudy (g3n3sis08):

Yeah.

OpenStudy (devonhoward15):

where is the vertex?

OpenStudy (devonhoward15):

under or below x-axis?

OpenStudy (devonhoward15):

and i have another like this can you help?

OpenStudy (g3n3sis08):

it is below.. you have to study completing squares otherwise it will be really difficult.

OpenStudy (devonhoward15):

thanks

OpenStudy (devonhoward15):

can you help with another?

OpenStudy (g3n3sis08):

https://www.youtube.com/watch?v=xGOQYTo9AKY check out this youtube video, im sure it'll help.

OpenStudy (g3n3sis08):

And this one also for discriminant https://www.youtube.com/watch?v=lGZNaoHGsM8

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