Another Maths Question...?

Question

Removing Brackets... What is 3 (x-3) -6 (3x-5)

2. What is 4 (2x-8) -2 (2x-4)? Tell me how you did it as well please!

Cheers

Answer 1

You always want to rememer the Order of Operations - PEMDAS, which means Parentheses, Exponents, Multiply, Divide, Add, Subtract, from left to right.

In the first problem, you first multiply the 3 times the (x-3) to get 3x - 3 and then you multiply the -6 times the (3x - 5) to get 18x + 30.  Put it all together and you get 3x - 3 - 18x + 30, gather like terms and you end up with 15x + 27.

So in the second problem... first you do 4(2x - 8), and0i It becomes 8x - 32.

Then... do the same with the 2(2x - 4) and you get 4x - 8.

Then put it all together, 8x - 32 - 4x - 9, gather like terms, and you get 4x - 41

I've put two links to math help sites below that are pretty good.

Hope this helps  :)

Answer 2

You have to multiply through each term in the brackets.  So...

1.  3 (x-3) -6 (3x-5)=

(3x-9) -6 (3x-5)=

(-18x+54) (3x-5)=

-54x^2+80x+162x-270=

-54x^2+242x-270

2.  4 (2x-8) -2 (2x-4)=

(8x-32) -2 (2x-4)=

(-16x+64) (2x-4)=

-32x^2+64x+128x-256=

-32x^2+192x-256

Answer 3

Problem 1: You are being asked what is 3 * (X - 3) MINUS 6 * (3X - 5). You must always evaluate the expressions with the parentheses first.

When multiplying an expression inside parentheses by a number on the outside, you must multiply all parts of the expression by the number on the outside.

3(X-3) = (3*X) - (3*3) = (3X - 9)

and

6(3X - 5) = (6*3X) - (6*5) = (18X - 30)

Now you need to put the minus sign back in and evaluate the rest of the expression:

(3X - 9) - (18X - 30)

Because all of the signs are minus signs, the order of operation doesn't matter, so you can rewrite this as:

3X - 9 - 18X - 30

and then one more rearrangement...

3X - 18X - 9 - 30

which is the same as:

+3X + -18X + -9 + -30

You can now evaluate the two parts of the expression:

+3X + -18X = -15X

and

-9 + -30 = -39

Now put the two parts back together for the final answer:

-15X - 39

Problem 2:

4 (2X-8)  MINUS 2 (2x-4)

= 4*(2X) - 4*(8) MINUS 2*(2X) - 2*(4)

= (8X - 32) MINUS (4X - 8)

= 8X - 32 - 4X - 8

= 8X + -32 + -4X + -8

= 8X + -4X + -32 + -8

= 4X - 40

After a while you won't need to rearrange the X variables next to each other. You'll just know that you need to combine the variables and the numbers, and you can do that in your head.

By the way, everyone else is wrong about multiplying the second half of the first equation by -6. Remember your order of operations! You don't put the minus sign next to the six back into play until you have finished evaluating the expressions.

Answer 4

1. 3(x-3) - 6(3x-5) = 3x-9-18x+30

                          = 21-15x

2. 4(2x-8) - 2(2x-4) = 8x-32-4x+8

                            = 4x-24

To remove the brackets, multiply the number outside of the brackets with each of the stuff inside. Remember the signs too.

Answer 5

3 (x-3) -6 (3x-5)

3x-9-18x+30

21-15x

>>>>>>>>>>>>>>>>>>>>>>>>>>>

4 (2x-8) -2 (2x-4)

8X-32-4x+8

4x-24

Answer 6

Answer for 3 (x-3) -6 (3x-5) is -15x-21

Answer for 4 (2x-8) -2 (2x-4) is 4x-24

First remove the brackets like this

4 (2x-8) -2 (2x-4)

=8x-32-4x+8

after that simplify it

8x-32-4x+8

=4x-24

Answer 7

Ok they are wrong. When you multiply to get rid of parenthesis, you have to use the distributive property, like this:

3(X-3) becomes 3 x X and 3 x -3 and once you multiply it, 3X -9.

same rule applies to the other half:

-6(3X-5) becomes -6 x 3X and -6 x -5 and once you multiply it -18X +30

**remember two negative signs make a positive sign when you multiply

then you write it all out and simplify by combining like terms:

3X - 9 -18X + 30

-18X + 3X + 30 - 9

15X + 21

does this make sense? try the next one by yourself and email me if you have any questions.