My son is learning signed numbers at school. It's been years since I've done this! Can someone please help explain this to me so I can better help him?
Here is an example problem:
3²(-4)²/-1
Following the order of operations you would solve for 3² and (-4)² giving you 9 and -16.
Then you'd multiply 9 by 16 giving you -144.
The problem would then be -144/-1 and the end result would be +144. Right?
I was wrong. The correct answer [according to the book] is +5. Please help me figure this out! I just don't understand anymore!! Haha.
Thanks!
2007-10-31 05:13:26 · 15 answers · asked by Karma Lucille 1 in Science & Mathematics ➔ Mathematics
Well, actually, with the way you've written it, (-4)^2 = 16, not -16.
The answer, as far as I can tell, is -144.
2007-10-31 05:17:19 · answer #1 · answered by spindoctoradam 3 · 0⤊ 0⤋
Haha indeed! The book is wrong. Period.
The current buzzword for remembering the order in which mathematical operations are to be performed, is
BEDMAS
Brackets first
Exponents next
Division next
Multiplication
Addition
Subtraction
In that order, reading from left to right.
For your problem, 3^2(-4)^2/-1
B: nothing to do.
E: We do (-4)^2, =-4 X -4, =+16
We now have 3^2(16) / -1
3^2 next (we're still doing E stuff)
3^2=9
So far, 9(16) /-1
D: -9(16)
M: -144
2007-10-31 12:26:10 · answer #2 · answered by Grampedo 7 · 0⤊ 0⤋
Because the -4 is in parentheses, they come first, then the exponent of 2. So it is -4 times -4 which is positive 16. You had it as -16. But still it would be -144, not +5
2007-10-31 12:18:57 · answer #3 · answered by hayharbr 7 · 0⤊ 0⤋
(-4)² is actually (-4)*(-4) = 16 and not -16.
Also /-1 makes sense only if it is /(-1), ie divided by (-1).
In any case, the problem statement is incorrect. You can't have a ² on the 4 if you want to get close to the answer. THe problem should look similar to this:
3² - (-4)/-1 = 9 - 4 = 5
2007-10-31 12:35:55 · answer #4 · answered by fouman1 3 · 0⤊ 0⤋
I believe the problem should be written like this:
3²-(4)²/-1 = 9-16/-1 = -5/-1 = +5
2007-10-31 12:19:58 · answer #5 · answered by don_sv_az 7 · 0⤊ 0⤋
Almost right! (-4)^2 = +16.
Think about it: it's (-4)(-4) and, you know that - - = + when multiplying.
Easy mistake to make. See the difference:
-4^2 = -16, but (-4)^2 = +16
However, there is no way the answer is +5.
2007-10-31 12:19:46 · answer #6 · answered by Marley K 7 · 0⤊ 0⤋
Your problem as stated: 3²(-4)²/-1
It groups like this:
((3^2) * ((-4)^2)) / (-1)
and works out like this:
3^2 = 3*3 = 9
(-4)^2 =- 4*-4 = 16
16*9 = 144
144/-1 = -144
2007-10-31 12:26:47 · answer #7 · answered by credo quia est absurdum 7 · 0⤊ 0⤋
No, sorry. When you square negatives, you multiply -4*-4 which gives you +16 then do everything else you said. I don't know why that would possibly be +5 from the problem you gave.
2007-10-31 12:17:34 · answer #8 · answered by The Salmon Of Doubt 1 · 0⤊ 0⤋
3^2 =9
-4^2 = 16
9-16= -5
-5/-1 = 5
2007-10-31 12:23:35 · answer #9 · answered by willmiller82 2 · 0⤊ 0⤋
- 4 x -4 = 16......you loose the negative sign because (-)(-)= (+)
so it is
9 x 16 = 144
144/-1 = -144
your book is wrong......
the only way you would get 5 is if the problem said
[(3)squared - (-4) squared] / -1
2007-10-31 12:21:56 · answer #10 · answered by Anonymous · 0⤊ 0⤋