SOLUTION: for the function y=x2-4x-5, perform the following tasks: a) Put the function in the form y=a(x-h)2 +k ....the 2 after x is x squared, and the 2 after h is (x-h)squared b)what is

Algebra ->  Functions -> SOLUTION: for the function y=x2-4x-5, perform the following tasks: a) Put the function in the form y=a(x-h)2 +k ....the 2 after x is x squared, and the 2 after h is (x-h)squared b)what is       Log On


   



Question 31878: for the function y=x2-4x-5, perform the following tasks:
a) Put the function in the form y=a(x-h)2 +k ....the 2 after x is x squared, and the 2 after h is (x-h)squared
b)what is the line of symmetry?
c) Graph the function using the equation in part a. Explain why it is not necessary to plot points to graph when using y=a(x-h)2 +k (the 2 after (x-h) is squared
d) how does this graph compare to the graph of y=x2(xsquared)

Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
+y=x%5E2-4x-5+

2a=-4
--> a = -2
and so a%5E2+=+4
+y=x%5E2-4x%28%2B4-4%29-5+ --> the +4-4 is zero, so we haven't actually altered the equation.

+y=%28x%5E2-4x%2B4%29-4-5+
+y=%28x-2%29%5E2-4-5+
+y=%28x-2%29%5E2-9+
+y=%28x-2%29%5E2%2B%28-9%29+ which is now of the form required.

b. Line of symmetry is x=2

c. We know the apex of the curve...it is (2,-9) and the x%5E2 term is positive, meaning it is u-shaped rather than n-shaped. So we get +graph%28300%2C300%2C-4%2C8%2C-10%2C4%2Cx%5E2-4x-5%29+. However, purely looking at the equation in this form does not "instantly" tell us the intercepts on the axes... some algebra, minimal yes, is still required.

d. y=x%5E2 moved by 2 units to the right gives y=%28x-2%29%5E2 and then this moved by 9 units down is given by y=%28x-2%29%5E2+-+9

Here are all 3 stages: y=x%5E2, y=%28x-2%29%5E2 and y=%28x-2%29%5E2-9 on the same scales, so you can see them:

+graph%28300%2C300%2C-4%2C8%2C-10%2C20%2Cx%5E2%29+
+graph%28300%2C300%2C-4%2C8%2C-10%2C20%2C%28x-2%29%5E2%29+
+graph%28300%2C300%2C-4%2C8%2C-10%2C20%2C%28x-2%29%5E2-9%29+

jon.