SOLUTION: how do you write y=(x-4)(x+2) in standard form? with the standard form of the equation use the quadratic formula to identify the x-value of the vertex. use the quadratic formula

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: how do you write y=(x-4)(x+2) in standard form? with the standard form of the equation use the quadratic formula to identify the x-value of the vertex. use the quadratic formula       Log On


   

Question 1024238: how do you write y=(x-4)(x+2) in standard form?
with the standard form of the equation use the quadratic formula to identify the x-value of the vertex. use the quadratic formula with the vertex -b/2a then substitute the x-value of the vertex into the original equation to find the y-value of the vertex then write the coordinates of the vertex. what are the 3 points to graph an parabola? PLEASE HELP
Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+y+=+%28+x+-+4+%29%2A%28+x+-+2+%29+
+y+=+x%5E2+-+4x+-+2x+%2B+8+
+y+=+x%5E2+-+6x+%2B+8+
This is in the form:
+y+=+a%2Ax%5E2+%2B+b%2Ax+%2B+c+, where
+a+=+1+
+b+=+-6+
+c+=+8+
------------
The formula for x-value of vertex is:
+x%5Bv%5D+=+-b%2F%282a%29+
+x%5Bv%5D+=+-%28-6%29+%2F+%28+2%2A1+%29+
+x%5Bv%5D+=+6%2F2+
+x%5Bv%5D+=+3+
--------------
+y+=+x%5E2+-+6x+%2B+8+
+y%5Bv%5D+=3%5E2+-+6%2A3+%2B+8+
+y%5Bv%5D+=+9+-+18+%2B+8+
+y%5Bv%5D+=+-9+%2B+8+
+y%5Bv%5D+=+-1+
----------------
The vertex is at ( 3,-1 )
--------------------
The other 2 points you can plot are:
+y+=+%28+x+-+4+%29%2A%28+x+-+2+%29+
+0+=+%28+4+-+4+%29%2A%28+4+-+2+%29+
( 4,0 )
and, also:
+y+=+%28+x+-+4+%29%2A%28+x+-+2+%29+
+0+=+%282+-+4+%29%2A%28+2+-+2+%29+
( 2,0 )
---------
Here's the plot:
+graph%28+400%2C+400%2C+-3%2C+8%2C+-3%2C+8%2C+x%5E2+-+6x+%2B+8+%29+

Answer by MathTherapy(10549) About Me  (Show Source):
You can put this solution on YOUR website!

how do you write y=(x-4)(x+2) in standard form?
with the standard form of the equation use the quadratic formula to identify the x-value of the vertex. use the quadratic formula with the vertex -b/2a then substitute the x-value of the vertex into the original equation to find the y-value of the vertex then write the coordinates of the vertex. what are the 3 points to graph an parabola? PLEASE HELP 
Duplicate! See No. 1024230