Write an equation for the parabola with a vertex at (2, -1) and y-intercept 5.

Question

saifoo.khan · Answer

$$y = (x - 2)^2 -1$$

amistre64 · Answer

when x=0 that equals 3 tho, not 5

saifoo.khan · Answer

Messed up.. o_O

saifoo.khan · Answer

Yeah..

saifoo.khan · Answer

figured//

amistre64 · Answer

gotta scale it right?

amistre64 · Answer

5 = a(-2)^2-1

amistre64 · Answer

its a good start tho, get the basic down and fidget with it

anonymous · Answer

That was what the question asked, I am confused on how to calculate (a)

amistre64 · Answer

a is just a single unknown that can be algebraed into submission

amistre64 · Answer

add 1 and divide off the (-2)^2

anonymous · Answer

My algebra teacher said the answer was $$3/2(x-2)^{2}$$

anonymous · Answer

PLus 1 at the end sorry

amistre64 · Answer

almost, missing the -1 at the end tho

anonymous · Answer

oh minus?

anonymous · Answer

Ok so how did he get 3 halves?

amistre64 · Answer

5 = a(-2)^2 - 1
+1                +1
----------------
  6 = a(4)
 /4     /4
---------
6/4 = a

amistre64 · Answer

this is basic equation manipulations; you will need to become quite adept at it for further math skills

anonymous · Answer

You put in the y intercept (5) in for x?

amistre64 · Answer

when x=0, y=5  so we zero out the x and replace y by 5

amistre64 · Answer

y = a(x-2)^2 - 1

5 = a(-2)^2 - 1

anonymous · Answer

Is it also possible to substitute h and k as well instead?

amistre64 · Answer

h and k are your vertex elements

amistre64 · Answer

we plugged those in to determine "a"

anonymous · Answer

oh ok i get it (hopefully) thank you

amistre64 · Answer

practice helps :)

saifoo.khan · Answer

Practise makes a man perfect. ;)