Question

Are the expressions –0.5(3x + 5) and –1.5x + 2.5 equivalent? Explain why or why not.

Answer 1

We can check this two ways: distributing the -0.5, and plugging in a number for x.

First, we can check this by distributing the -0.5.  Our equation becomes:

-1.5x -2.5 = -1.5x + 2.5

Clearly, this is not true.  We can show this one more time by plugging in a number for x.  I will use 2.

$-0.5(3*2+5)=-1.5*2+2.5$

Now, we evaluate both sides and see if they are equal.

-3 - 2.5 = -3 + 2.5

-5.5 = 0.5

Clearly, this is not true.  These expressions are not equivalent.

Answer 2

Using the distributive property to expand the first expression, you would get -1.5x - 2.5. Since the constant term does not have the same sign as the second expression, the two expressions are not equivalent. Also, if you substitute in a value for x and evaluate each expression, the values will not be equal.