Question

http://media.education2020.com/evresources/3109/3109-08/3109-08-03/3109-08-03-assessment/3109-08-03-05.png

Armando used algebra tiles to represent the product 3x(2x-1).

Which is true regarding Armandos use of algebra tiles?

a)He used the algebra tiles correctly.
b)He did not represent the two original factors correctly.
c)The signs on some of the products are incorrect.
d)Some of the products do not show the correct powers of x.

Answer 1

@pitamar would you happen to know this one

Answer 2

Well I haven't seen this kind of diagram in my life.. but let's see.

The algebraic result is:
$$
3x(2x - 1) = 3x \cdot 2x - 3x = 6x^2 - 3x
$$
But the tiles show
$$
2x^2 + 8x -4 - x = 2x^2 + 7x - 4
$$
So the tiles are not used correctly, and therefore the answer isn't 'a'.

Upper side is meant to be one factor, and indeed there are three x's there, so it represents the 3x.
The left side has two x's and a '-' sign which will stand for the -1.. so it represents (2x-1).
So 'b' is not the answer then..

The signs.. Well, anything that doesn't involve multiplying by the negative -1 remains positive.. and anything that does became negative. so 'c' is not the answer as well

So now we're left with 'd', and indeed there is a problem with the powers.
The problem is that he used two of the 'x' on the top as if they were '2' when multiplying. But he still 'represented' the factor correctly, just didn't use it correctly.
I'd say D is the best answer.

Answer 3

wow you were right you are the best mathematics person ever @pitamar

Answer 4

Ah thanks but that's a bit of an exaggeration

Answer 5

lol right @pitamar