# Algebra

Discussion in 'General Discussion' started by speedyj, 6 Jun 2010.

1. speedyj

# Location: Suffolk

a=2, b=-4, c=-3

a³ - 2b - 4c²

2. SideWinder

# Location: NW5

(2x3) - (2x-4) - (4x-3x2).

I think...i got a C for Maths GCSE.

3. Ahleckz

# Location: Glasgow

Edited so noone knows I was *ahem* right *ahem*

Last edited: 6 Jun 2010
4. Fegruson

5. SideWinder

# Location: NW5

I wasn't going to do his homework for him...!

6. Fegruson

# Location: Derby

Not even sure it's correct tbh!

7. fidget

8. Lydzor

# Posts: 781

I got -20 also.

9. Cosimo

10. icysniper

# Location: South Wales

hmm i get 124

8 - -8 - -108

= 8+8+108 = 124

EDIT: my bad lemme work it out again

yeh got -20, for some reason i thought it was cubed for C, wtf was i thinking?

11. DB_SamX

# Location: Winchester

Would be an F really here.

12. fidget

13. Hamster

# Location: location: location

-20. This is very basic year 8 maths.

14. Lydzor

# Posts: 781

I'm guessing people are misunderstanding powers and how to calculate minus numbers.

15. SideWinder

# Location: NW5

...was my method correct by the way?

16. speedyj

# Location: Suffolk

a=2, b=-4, c=-3

a³ - 2b - 4c²

2³ -8x(-4) -4x(-3)²

now sort out the numbers:
8 not 6!!!! It's 2x2x2 = 4x2 = 8
+ 32 minus times a minus is a plus
- 36 do it carefully, (-3)² = +9, -4x9 = -36
= 4

This is the explanation on a website my daughter has been pointed to by her teacher.

17. Skillmister

# Location: Wales

(2x2x2) - (-4x2) - (4x(-3x-3))
=
8 - -8 - (4x9)
=
16--36
=
-20

edit: its -20

18. TheCenturion

# Posts: 12,755

Come on people this isn't hard at all!

I'll even put it into words!

2 cubed is 8

2 times -4 is -8

-3 squared is 9, and 9 x 4 is 36

8 take away negative 8 is 16. 16 take away 36 is -20

That was simples.

19. Lightnix

# Location: from the internet

Where'd you get -8x(-4) from then?

20. speedyj

# Location: Suffolk

Its not my expression, I don't understand where that comes from either, it is on the website that my daughter was pointed to.

It looks wrong to me also.