General Discussions

**Brian07002** · 02-20-2009, 05:17 PM

Ok here is another Algebra problem that I am having some problems with:

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?

Can someone please take me through this problem step by step?

Thanks again!

**NullPointer** · 02-20-2009, 05:51 PM

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?
-49 - [ -20 - 9 ] + 10 = ?
-49 - [ -29 ] + 10 = ?
-49 + 29 + 10 = -10

**Decaf** · 02-20-2009, 06:38 PM

Quote:

Originally Posted by Brian07002

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?

-7² - [-20 - (-3)²] - (-10) =
-49 - [-20 - 9] + 10 =
-49 - [-29] + 10 =
-49 + 29 + 10 =
-49 + 39 =
-10

**andrei155** · 02-20-2009, 10:10 PM

These all seem like rather simple questions. What do you need this for?

**patrickson** · 01:43 AM

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?
49 - [- 20 - 9 ] +10 = ?
-10 + 49 - [ -20 - 9] = ?
39 - 29 = 10

"10" <<<<<< answer

**ultra** · 02-23-2009, 09:09 AM

-7² - [ -20 - ( -3 )² ] - ( -10 )
49 - ( - 20 - 9 ) +10
49 + 29 + 10
88

**NullPointer** · 02-23-2009, 05:19 PM

Quote:

Originally Posted by ultra

-7² - [ -20 - ( -3 )² ] - ( -10 )
49 - ( - 20 - 9 ) +10
49 + 29 + 10
88

-7² = -49
(-7)² = 49

**jv17** · 08:56 PM

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?

49 - (-20 - 9) + 10 = ?
49 - (-29) +10 = ?
49+ 29 + 10 = 88

**serandfae** · 02-23-2009, 09:03 PM

Quote:

Originally Posted by NullPointer

-7² = -49
(-7)² = 49

-7² = 49
(-7)² = 49
-(7²) = -49

tim

**Decaf** · 02-23-2009, 11:59 PM

Quote:

Originally Posted by serandfae

-7² = 49
(-7)² = 49
-(7²) = -49

tim

-7² = -49
-(7²) = -49
(-7²) = -49
(-7)² = 49

**jamestl2** · 02-24-2009, 12:04 AM

http://www.google.com/search?q=-7^2+-+(-20+-+(+-3+)^2)+-+(-10)&btnG=Search

**sairam** · 02-24-2009, 01:30 AM

-7² - [ -20 - ( -3 )² ] - ( -10 ) = ?
-(7x7)-[-20-(-3x-3)]-(-10)
-(49)-[-20-(9)]-(-10)]
-49-[-29]+10
-49+29+10
-10 = Answer

**serandfae** · 02-24-2009, 06:22 AM

Quote:

Originally Posted by Decaf

-7² = -49
(-7²) = -49

Is that the "new math?"

Is this the result in mathematics in which we saw a similar effect in language arts when they axed phonics and spelling?

tim

**jamestl2** · 02-24-2009, 12:01 PM

Tim, I think it's because via order of operations, squaring comes before negation. So -7^2 is basically the same thing as -(7^2).

**serandfae** · 02-24-2009, 03:12 PM

Like I said, the new math. Complete and total rubbish. I asked a math teacher, who agrees with you, but this comes from a generation in which kids don't have to memorize multiplication tables, and kids are expected to, even taught to, depend on calculators.

tim

**jamestl2** · 02-24-2009, 04:01 PM

How long has it been that way for? If not for very long, then why change it?

Technically I believe it could go either way, and parentheses should be used no matter what in situations like this to avoid confusion.

**Decaf** · 02-24-2009, 06:34 PM

Quote:

Originally Posted by serandfae

Like I said, the new math. Complete and total rubbish. I asked a math teacher, who agrees with you, but this comes from a generation in which kids don't have to memorize multiplication tables, and kids are expected to, even taught to, depend on calculators.

tim

Lies, in 4th grade I was the only kid to finish my 60 math problems in 60 seconds. 1 second/problem, boy it was fun. Using a calculator would only get you ~20 problems.

**serandfae** · 02-24-2009, 07:10 PM

So that was you; I could direct you to an army of parents who decided to homeschool because their kids were directed to use calculators, were not taught to spell (and the rationale was because computers have spell check!) and the kids ran the schools because no one was disciplined. Why else would companies like Sylvan and Hooked on Phonics do such a booming business?

In any case, modern calculators and the math teacher I asked agree with you, though I still say writing an equation in such a manner invites confusion, and anyone caught doing so should be mercilessly flogged. I disliked most of my math teachers. I could do calculus problems in my head, and got in trouble for not showing my steps. Seemed a waste of effort, given that I got the answers right, and I can think a LOT faster than I can write.

tim

**Decaf** · 02-24-2009, 07:33 PM

Quote:

Originally Posted by serandfae

So that was you; I could direct you to an army of parents who decided to homeschool because their kids were directed to use calculators, were not taught to spell (and the rationale was because computers have spell check!) and the kids ran the schools because no one was disciplined. Why else would companies like Sylvan and Hooked on Phonics do such a booming business?

In any case, modern calculators and the math teacher I asked agree with you, though I still say writing an equation in such a manner invites confusion, and anyone caught doing so should be mercilessly flogged. I disliked most of my math teachers. I could do calculus problems in my head, and got in trouble for not showing my steps. Seemed a waste of effort, given that I got the answers right, and I can think a LOT faster than I can write.

tim

I completely agree, there are a lot of kids who are not being challenged but then there are the kids who's brains just can't comprehend "simple" high school topics.

People are becoming more and more reliant on simple easy solutions. If a topic is "to hard" a large majority of kids/adults will just stop. Its really sad, but there doesn't seem to be a way to solve it. (Fyi, These "No Child Left Behind Standard Test B***S*** will NOT help anyone).

**serandfae** · 02-24-2009, 07:51 PM

Sounds like you should contribute to the Rename No Child Left Behind thread in the Politics and Religion Forum.

One of my contributions was No Educated Children Left.

Back to the OP, yeah, according to the "new math", -10 is the answer.

tim