Algebra

[nev7770]

My Grand-Daughter has asked me to help her with her Maths. Can any of you help me please.

(x+2)(x-4) =
(2x+5)(3x-2)=
(3x+4)(2x-5)=
(4x+8)3x-2)=
(3x+2y)(2x+3y)=
(x-4)(2x-6)=
(3x+2)2 =
(3x+4)2 =
(7x+2)2 =
(-5x-7)2 =
(x+y)2 =
(4x-2y)2 =

Many Thanks in Advance

Ned

[factor-fiction]

This is the youtube link

http://www.youtube.com/watch?v=iB3L5csbB4E

[Psybbo]

http://revisemaths.org.uk/algebra/expanding-double-brackets/

[Buenchico]

Simply stick to the rule that everything inside one bracket has to be multiplied by everything inside the other. (i.e. ensure that you cover all possible pairings).

For example, taking the third one, to expand (3x+4)(2x-5):
multiplying 3x by 2x gives 6x²
multiplying 3x by -5 gives -15x
multiplying 4 by 2x gives 8x
multiplying 4 by -5 gives -20

Hence (3x+4)(2x-5) = 6x² - 15x + 8x -20 = 6x² - 7x -20


Taking the last one, (4x-2y)² = (4x-2y)(4x-2y)
multiplying 4x by 4x gives 16x²
multiplying 4x by -2y gives -8xy
multiplying -2y by 4x gives -8xy
multiplying -2y by -2y gives +4y²

Hence (4x-2y)² = (4x-2y)(4x-2y) = 16x² -8xy -8xy +4y² = 16x² -16xy +4y²