General Discussions

**Brian07002** · 08:27 PM

Hi,

For the Algebra Minded people on this forum, can one of you show me the steps to solve this problem?

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]

I use the PEMDAS Mechanics but I can't seem to wrap this equation up correctly for some reason...I would appreciate anyone with the Algebra skills to help me solve this.

Thank you

**Decaf** · 08:53 PM

Quote:

Originally Posted by Brian07002

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ (-3) -8 ] -4² + 2 [ 3 ( -3) + 9 ]
3 + 4 [ 24 ] -4² + 2 [ -9 + 9 ]
3 + 4 * 24 + 16 + 2 + 0
3 + 48 + 16 + 2
(3 + 48) + (16+2)
51 + 18
=69?

**Brian07002** · 02-09-2009, 09:12 PM

I found the answer to it, but I am still having a problem with the steps. The answer is 25 not 69, but you brought the steps back to my memory...I just need to re-write it out and I should get the right answer.

**Decaf** · 10:08 PM

3 + (4 * ((6 - 9) - 8)) + ((-4) * (-4)) + (2 * ((3 * (2 - 5)) + 9)) = -25

Google

**serandfae** · 02-09-2009, 10:13 PM

Here it is with the steps included:
Order of operation "Pretty Please, My Dear Aunt Sally"
Powers, parentheses, Multiplication, Division, Addition, Subtraction

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ ( 6-9 ) -8 ] 16 + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ ( -3 ) -8 ] 16 + 2 [ 3 ( -3 ) +9 ]
3 + 4 [ -11 ] 16 + 2 [ 0 ]
3 + -704 + 0
-701

tim

**andrei155** · 02-09-2009, 10:25 PM

BEDMAS
BracketsExpontentsDivisionMultiplicationAdditionSubtraction

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
= 3+4((-3)-8) - 16 + 2(3(-3) + 9)
= 3 + 4( -11 ) - 16 + 2(-9 + 9)
= 3 - 44 - 16 +2(0)
= 3 - 44 - 16 + 0
= -57

**andrei155** · 02-09-2009, 10:30 PM

Quote:

Originally Posted by serandfae

Here it is with the steps included:
Order of operation "Pretty Please, My Dear Aunt Sally"
Powers, parentheses, Multiplication, Division, Addition, Subtraction

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ ( 6-9 ) -8 ] 16 + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ ( -3 ) -8 ] 16 + 2 [ 3 ( -3 ) +9 ]
3 + 4 [ -11 ] 16 + 2 [ 0 ]
3 + -704 + 0
-701

tim

-4² = -16 not 16
(-4²) = 16

In this case, the negative sign is not included in the operation.

After you've done the exponent operation, in our case, we would be using it to add or subtract. You've magically turned this into multiplication.

-704 is the product of 4, -11, and 16. In reality, you were to multiply 4 and -11, then subtract 16 from the value - giving you -60. 3 is the to be added, giving you -57

**Decaf** · 10:38 PM

Please Excuse My Dear Aunt Sally
Parentheses/Powers, Multiplication, Division, Addition, Subtraction

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) + 9 ]
3 + 4 [ (-3) + -8 ] -4² + 2[3(-3)+9]
3 + 4[-11] -4² + 2[-9 + 9]
3 + -44 + -4² + 2[-9 + 9]
3 + -44 + 16 + 2[0]
3 + -44 + 16 + 0
-41 + 16
= -25

andrei155 - Its (-4)² Not -(4)².

**andrei155** · 02-09-2009, 10:35 PM

Quote:

Originally Posted by Decaf

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ (-3) -8 ] -4² + 2 [ 3 ( -3) + 9 ]
3 + 4 [ 24 ] -4² + 2 [ -9 + 9 ]
3 + 4 * 24 + 16 + 2 + 0
3 + 48 + 16 + 2
(3 + 48) + (16+2)
51 + 18
=69?

(-3) -8 is a subtraction. It's (-3) - 8... not (-3)(-8).
-4² - the negative is not squared, only the 4 is. (-4²), only in this situation will the negative also be squared.
It's 2 x 0, not 2 + 0.

**andrei155** · 02-09-2009, 10:37 PM

Quote:

Originally Posted by Decaf

Please Excuse My Dear Aunt Sally
Parentheses/Powers, Multiplication, Division, Addition, Subtraction

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) + 9 ]
3 + 4 [ (-3) + -8 ] -4² + 2[3(-3)+9]
3 + 4[-11] -4² + 2[-9 + 9]
3 + -44 + -4² + 2[-9 + 9]
3 + -44 + 16 + 2[0]
3 + -44 + 16 + 0
-41 + 16
= -25

The - in -4² is not included in the square.

**Decaf** · 10:42 PM

Quote:

Originally Posted by andrei155

The - in -4² is not included in the square.

Sorry, but yes it is. They would separate it otherwise as -(4*4).

**andrei155** · 02-09-2009, 10:46 PM

The only time the negative would be included, is when brackets are added around it. Otherwise, the square applies to the number attached. -4² is:
- 4² The 4² would occur first, in order of operations (resulting 16) and the the negative would be added later.

(-4)² results in a positive 16.

**andrei155** · 10:51 PM

http://www.purplemath.com/modules/negative4.htm

Quote:

Now you can move on to exponents, using the cancelation-of-minus-signs property of multiplication. For instance, (3)2 = (3)(3) = 9. In the same way:

Simplify (–3)2
- (–3)2 = (–3)(–3) = (+3)(+3) = 9

Note the difference between the above exercise and the following:

Simplify –32
- –32 = –(3)(3) = (–1)(9) = –9

The exponents don't show up so well in the quote. Visit the above url.

**andrei155** · 10:54 PM

Quote:

The negative number must be enclosed by parentheses to have the exponent apply to the negative term.
Note that (-2)^4 = -2 * -2 * -2 * -2 = 16
and -2^4 = -(2 * 2 * 2 * 2) = -16

http://www.321know.com/exp-int-eval-exp.htm

**EvcRo** · 02-10-2009, 05:53 AM

3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
=3+4 *(-11)- 16 + 2*0
=3-44-16
=3-60
=-57

**Decaf** · 02-10-2009, 07:03 AM

Ya, it seems that my previous teachers taught me to add the parentheses to the number. Weird, the correct answer is -57.

**amerie** · 02-10-2009, 08:14 AM

algebra?

**serandfae** · 02-10-2009, 03:17 PM

Spaces should have been put in to avoid confusion:

3 + 4 [ ( 6-9 ) - 8 ] - 4² + 2 [ 3( 2-5 ) + 9 ]

There's a HUGE amount of difference between x - 4² and x -4². It's the difference between x - 16 and 16x. An operator placed directly in front of a number is its value. Try punching that into a calculator both ways (with the spaces and without) and you'll see the difference.

tim

**juliensimon** · 02-10-2009, 05:18 PM

blame it on the spaces

**jv17** · 02-10-2009, 05:25 PM

let me show my solution:
try to solve the values that are inside of it
3 + 4 [ ( 6-9 ) -8 ] -4² + 2 [ 3 ( 2-5 ) +9 ]
3 + 4 [ ( -3 ) -8 ] -4² + 2 [ 3 ( -3 ) +9 ]
3 + 4 [ -11 ] 16 + 2 [ -9 +9 ]
3 + 4 ( -11 ) 16 + 2 ( 0 )
-77 + 16
= - 61