+0  
 
0
42
2
avatar

why is negative 5 in parenthesis to the 2nd power positive 25, and when it doesn't have parenthesis it equals negative 25

Guest Sep 8, 2017
Sort: 

2+0 Answers

 #1
avatar+4476 
+3

To see why...you need to know these things:

 

a2  =  a * a

 

A negative number times a negative number equals a positive number, e.g.       -3 * -4  =  12

 

Exponents come before multiplication in the order of operations, e.g.     6 * 32  =  6 * 9  =  54

 

And...     -4  =  -1 * 4

 

Try writing out the multiplication for your question. Can you figure it out now?  smiley

hectictar  Sep 8, 2017
 #2
avatar+90136 
+2

Thanks hectictar, i'd just like to add a little more.

 

\((-4)^2=-4*-4 =+16\)

Maybe that one is fairly obvvious to you..

If not then look better at Hectictar explanation.    smiley

 

 \(\text{So why is }-4^2\;\;\text{different ?}\\\)

 

Welll... Lets say that -42 did equal +16 (which is doesn't) and see what happens

\(30-4^2=30-16=14 \)

But 

\(30-4^2\;\;also\;\;=-4^2+30\)

If -42 = +16 then this answer becomes 16+30 = 46   which is obviously wrong because I know the answer is 14  !!

 

so the best way to think of it is this

\(-4^2=-1*4^2=-1*16=-16\) 

 

I hope that, together with Hectictar's answer, helps :)

Melody  Sep 8, 2017

23 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details