## Graphing Parabola, negative x values

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
wp_913
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### Graphing Parabola, negative x values

Hi

I'm confused, a negative number with an exponent (exponentiation), will first have the exponent evaluated, and then have the opposite applied, ie. -2^2 = -4

However, if the negative number is enclosed with parentheses, (-2)^2, that indicates (-2) x (-2) = 4

So my question, when finding points for graphing a parabola, it appears from the examples I have studied that any negative values for x^2 always come out positive when evaluated in the quadratic equation, but there are no parentheses enclosing that value.

f(x) = ax^2 + bx + c

f(-2) = -2^2 + 4(-2) + 3 = -9, but all the examples that I study would evaluate this as f(-2) = (-2)^2 + 4(-2) + 3 = -1. But the parentheses are not shown, what rule or concept am I missing?

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Joined: Sun Feb 22, 2009 11:12 pm

### Re: Graphing Parabola, negative x values

Without seeing your book, it's hard to say what's going on. Does the book show the plug-and-chug as "-2^2 = 4", etc?

wp_913
Posts: 5
Joined: Mon May 16, 2011 12:01 am
Contact:

### Re: Graphing Parabola, negative x values

Hi

Not sure what the plug - chug means

This is what the book shows:

A negative number with an exponent (exponentiation), will first have the exponent evaluated, and then have the opposite applied, ie. -2^2 = -4

However, if the negative number is enclosed with parentheses, (-2)^2, that indicates (-2) x (-2) = 4

But in later chapters evaluating and graphing quadratic equations:

when finding points for graphing a parabola, it appears from the examples I have studied that any negative values for x^2 always come out positive when evaluated in the quadratic equation, but there are no parentheses enclosing that value.

f(x) = ax^2 + bx + c

f(-2) = -2^2 + 4(-2) + 3 = -9, but all the examples that I study would evaluate this as f(-2) = (-2)^2 + 4(-2) + 3 = -1. But the parentheses are not shown, what rule or concept am I missing?

Let me know if I can explain this better?