SOLUTION: Find values of a and k for a parabola containing the points given: y-k = a(x+3)^2 (-5,1)and (1,7) I've been working on this problem for a while, but I could use a little help.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Find values of a and k for a parabola containing the points given: y-k = a(x+3)^2 (-5,1)and (1,7) I've been working on this problem for a while, but I could use a little help.       Log On


   

Question 40097: Find values of a and k for a parabola containing the points given:
y-k = a(x+3)^2
(-5,1)and (1,7)
I've been working on this problem for a while, but I could use a little help. Thanks (:
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
+y-k+=+a%28x%2B3%29%5E2+

OK, put in the values (-5,1)
+y-k+=+a%28x%2B3%29%5E2+
+1-k+=+a%28-5%2B3%29%5E2+
+1-k+=+a%28-2%29%5E2+
+1-k+=+4a+
+1+=+4a+%2B+k+
or +4a+%2B+k+=+1+

and put in the values (1,7)
+y-k+=+a%28x%2B3%29%5E2+
+7-k+=+a%281%2B3%29%5E2+
+7-k+=+a%284%29%5E2+
+7-k+=+16a+
+7+=+16a+%2B+k+
or +16a+%2B+k+=+7+

So simultaneous equations
4a + k = 1
16a + k = 7

Subtract these to find a and then find k.

jon.