I can't solve these algebra equations would anybody be kind enough to help me?

Question

The first one

-3(2a-3b)+4(a-2b)=       ;a=3x+2y , b=-2y

The second one

3(x-2y+2(3y-x))=           ;x=a-2b , y=4b+3a
                                    a=1   ,  b=-2


And the third equation

-((3a+5b)-3(2a-5b)+4(5b-3a))=

a=4y+y  ,   b=x-3y,   x=-5,   y=4

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For the life of me I can't solve em correctly, I know the answers to all of them but I keep getting them wrong, 
 for the first I got -6x-4y ,the answer is -6x-6y

The second one I got -72 or -78 ,the answer is -75.

The third one I just don't get I got 106 or -84 ,the answer is 440

Answer

First you need to learn the basics, starting with correct presentation. You don't have an equation until you set something equal to something. -3(2a-3b)+4(a-2b)=  is an incomplete statement.

Second you need to learn what the symbols mean and only use them that way. The semicolon has no meaning, so you have a hole in the page there. We are not supposed to have to guess at what you are saying. The reason you can't solve these is you have to guess at what you are doing.

Third you are simply plugging in given values here, so all you have to do is to follow the steps for evaluation: no corner cutting.

z = -3(2a-3b)+4(a-2b)  Evaluate using PEDMAS.

z = -6a - 9b + 4a - 8b  Figure out a pattern you want to follow and add spaces in that pattern. That makes your work much easier to look at.

z = -2a -17b  Now you can substitute the given values.
----------------------------
z = -2(3x + 2y) - 17(-2y)  Evaluate.

z = -6x - 4y + 34y

z = -6x + 30y  <--  ANSWER

Do the others the same way.

I can't solve these algebra equations would anybody be kind enough to help me?

Responses (1)