helping me renew my skills-help on equation

[olemary]

I will give you the equation, then my question. Please help me to understand this so that I can pass this math and get my degree.

y=x^2 - 6x + 4

The formula is x= -b / 2a

Then it informs me to find the vertex and graph. It says that the coefficient of x^2 is understood to be 1 since there's no number in front of the variable. So a=1.
Okay, this I get!

Let's calculate the coordinates of the vertex. Find the x coordinate by substituting the formula. Notice that the formula has a minus sign in front of the letter b, but in this equation b has a value of -6. HUH???? MY QUESTION: WHERE DID THE NEGATIVE COME FROM??? I see a 6 in the equation, but it is not negative. How did this number come about???

I'm so lost and this is only the beginning of what I have to know for this module!
Can you help teach an old dog new tricks? Thanks for your help.

Mary

 

[galactus]

What?. That looks like a negative 6 to me.

\(\displaystyle x^{2}-6x+4\)

What if it were \(\displaystyle x^{2}+6x+4\)?. 6 and -6 are the same thing, huh?.

Maybe if we were talking absolute values, but we're not.

That's what you're saying.

Plug them in your vertex formula:

\(\displaystyle \L\\x=\frac{-(-6)}{2(1)}\)

 

[Mrspi]

I will give you the equation, then my question. Please help me to understand this so that I can pass this math and get my degree.

y=x^2 - 6x + 4

The formula is x= -b / 2a

Then it informs me to find the vertex and graph. It says that the coefficient of x^2 is understood to be 1 since there's no number in front of the variable. So a=1.
Okay, this I get!

Let's calculate the coordinates of the vertex. Find the x coordinate by substituting the formula. Notice that the formula has a minus sign in front of the letter b, but in this equation b has a value of -6. HUH???? MY QUESTION: WHERE DID THE NEGATIVE COME FROM??? I see a 6 in the equation, but it is not negative. How did this number come about???

I'm so lost and this is only the beginning of what I have to know for this module!
Can you help teach an old dog new tricks? Thanks for your help.

Mary

When you see "-b" that means "the opposite of b"

If b = 2, then "- b" means "the opposite of 2," or -2.

If b = -6, then "-b" means "the opposite of -6," or 6.

 

[olemary]

I will give you the equation, then my question. Please help me to understand this so that I can pass this math and get my degree.

y=x^2 - 6x + 4

The formula is x= -b / 2a

Then it informs me to find the vertex and graph. It says that the coefficient of x^2 is understood to be 1 since there's no number in front of the variable. So a=1.
Okay, this I get!

Let's calculate the coordinates of the vertex. Find the x coordinate by substituting the formula. Notice that the formula has a minus sign in front of the letter b, but in this equation b has a value of -6. HUH???? MY QUESTION: WHERE DID THE NEGATIVE COME FROM??? I see a 6 in the equation, but it is not negative. How did this number come about???

I'm so lost and this is only the beginning of what I have to know for this module!
Can you help teach an old dog new tricks? Thanks for your help.

Mary

When you see "-b" that means "the opposite of b"

If b = 2, then "- b" means "the opposite of 2," or -2.

If b = -6, then "-b" means "the opposite of -6," or 6.

But, in the solution: it says x= -b over 2a= -(-6) over 2(1)=6 over 2=3
So again I ask, how did the 6 in the equation become a negative number? Can you clarify?
Thanks,
Mary

 

[skeeter]

ax² + bx + c

(1)x² + (-6)x + 4