I have a test tommorow and Im in grade 8 algebra 1

Could somebody walk me through these 2 questions so i know if im doing it right or not?

2(1-d) - (2d+1)

5(2-j) + (2j-3)

Cheers,

Sam

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- Aug 18th 2005, 02:08 PMwhy-do-i-have-to-registerDistributive property help
I have a test tommorow and Im in grade 8 algebra 1

Could somebody walk me through these 2 questions so i know if im doing it right or not?

2(1-d) - (2d+1)

5(2-j) + (2j-3)

Cheers,

Sam - Aug 18th 2005, 02:18 PMrgep
Let's look at 5(2-j) + (2j-3). I'll insert the implied multiplication sign to write 5 x (2-j) + (2j-3). We do the multiplication first (BODMAS). 5 x (2-j): multiplication distributes over addition, that is, a x (b+c) = (a x b) + (a x c), inserting () for clarity. Equally x distributes over -. So 5 x (2-j) = 5x2 - 5xj = 10 - 5j. So the total expression is (10 - 5j) + (2j - 3). We can gather terms (repeatedly using associative and commutative properties) to get (2j-5j) + (10-3). Reversing the distributive law 2j-5j = (2-5)j = -3j. So the answer is7 - 3j.

- Aug 18th 2005, 02:24 PMwhy-do-i-have-to-registerthnx
2(1-d) - (2d+1)

When multiplying the second equation is it -1x2d and -1x1 - Aug 18th 2005, 11:10 PMrgepQuote:

Originally Posted by**why-do-i-have-to-register**