I need to write -x^2 + 6x -8 in the form f(x) = a(x-h)^2 + k Is it f(x) = -1(x+3)^2 -17
H haliebre New member Joined Apr 4, 2006 Messages 43 Apr 9, 2006 #1 I need to write -x^2 + 6x -8 in the form f(x) = a(x-h)^2 + k Is it f(x) = -1(x+3)^2 -17
S soroban Elite Member Joined Jan 28, 2005 Messages 5,586 Apr 9, 2006 #2 Re: equations Hello, haliebre! I need to write \(\displaystyle -x^2\,+\,6x\,-\,8\) in the form \(\displaystyle f(x)\:=\:a(x\,-\,h)^2\,+\,k\) Click to expand... Factor out -1: \(\displaystyle \:f(x)\;=\;-(x^2\,-\,6x\,+\,8)\) Complete the square: \(\displaystyle \:f(x)\;=\;-(x^2\,-\,6x\) + 9 \(\displaystyle +\,8\) - 9\(\displaystyle ) \;= \;-(x^2\,-\,6x\,+\,9\,-\,1)\) \(\displaystyle \;\;f(x)\;=\;-[(x\,-\,3)^2\,-\,1] \;= \;-(x\,-\,3)^2\,+\,1\)
Re: equations Hello, haliebre! I need to write \(\displaystyle -x^2\,+\,6x\,-\,8\) in the form \(\displaystyle f(x)\:=\:a(x\,-\,h)^2\,+\,k\) Click to expand... Factor out -1: \(\displaystyle \:f(x)\;=\;-(x^2\,-\,6x\,+\,8)\) Complete the square: \(\displaystyle \:f(x)\;=\;-(x^2\,-\,6x\) + 9 \(\displaystyle +\,8\) - 9\(\displaystyle ) \;= \;-(x^2\,-\,6x\,+\,9\,-\,1)\) \(\displaystyle \;\;f(x)\;=\;-[(x\,-\,3)^2\,-\,1] \;= \;-(x\,-\,3)^2\,+\,1\)
G Gene Senior Member Joined Oct 8, 2003 Messages 1,904 Apr 9, 2006 #3 Hint: You can usually spot a wrong answer by pluging in a few values for x. f(0) = -0^2 + 6*0 -8 = -8 f(0) = -1(0+3)^2 -17 = -26 Not the same so not correct. ---------------- Gene
Hint: You can usually spot a wrong answer by pluging in a few values for x. f(0) = -0^2 + 6*0 -8 = -8 f(0) = -1(0+3)^2 -17 = -26 Not the same so not correct. ---------------- Gene
