Negative numbers squared: 5 squared - 2(5)(-4) + -4squared

5 squared - 2(5)(-4) + -4squared =
5x5-2(5x-4)-4x-4
25+40-16=49

I have been told the answer was 81. The problem I have is the -4squared at the end of the original equation.
My understanding is when the -4 is not in ( ) then the answer is still negative because you are squaring the number and not the negative. However, if the -4 is in ( ) then the answer is positive because you are squaring what is inside the ( ).

So should -4 squared = -16 or +16?

I do not know how to show the exponent on this forum. Please advise how to do so instead of writing the word squared.

Re: Negative numbers squared

liesl said:

5 squared - 2(5)(-4) + -4squared =....

Click to expand...

Does your problem look like:

\(\displaystyle 5^2 -2(5)(-4) + (-4)^2\).................(1)

or

\(\displaystyle 5^2 -2(5)(-4) + -4^2\)

If it looks like (1) - then you would get +16 and final answer 81.

Re: Negative numbers squared

The equation look like the second example and this would give me 49. Thank you.

Due to the + -, it's obvious to me that what is meant is (-4)^2, so answer is 81.
Tell your teacher that's very poorly stated.

After doing much research, the answer is 81. If I had to subtract -4^2 the answer would have been 49. The equation should have been written + (-4)^2 for better clarification. Because we all know, two negatives multiplied make a positive and we are adding the positive number and not a negative number. I thank every one for their help.

I am sure I will be back.
Liesl