Identify two expressions that will be equivalent to 2x^2−8x−10

when distributed. Enter the option with the lesser number first.

Option #1: 2x(x−4x−5)

Option #2: (2x+2)(x−5)

Option #3: 2x(x−5)+2(x−5)

Option #4: (x−5)(x−3)

Option #5: −6x−10

1 answer

To identify which options are equivalent to the expression \(2x^2 - 8x - 10\), let's first factor the original expression, if possible, and then distribute the expressions provided in the options.

Starting with \(2x^2 - 8x - 10\):

  1. Factoring: First, factor out the common factor of 2: \[ 2(x^2 - 4x - 5) \] Now, let's factor \(x^2 - 4x - 5\): We are looking for two numbers that multiply to \(-5\) and add to \(-4\), which are \(-5\) and \(1\). Therefore, \[ x^2 - 4x - 5 = (x - 5)(x + 1) \] So, \[ 2(x - 5)(x + 1) \]

Now we have \(2x^2 - 8x - 10 = 2(x - 5)(x + 1)\).

Now, let's check each option:

  1. Option #1: \(2x(x - 4x - 5)\) This option seems incorrect (the term "-4x" is off).

  2. Option #2: \((2x + 2)(x - 5)\) Distributing: \[ 2x \cdot x + 2 \cdot x - 5 \cdot 2x - 5 \cdot 2 = 2x^2 + 2x - 10x - 10 = 2x^2 - 8x - 10 \] This option is equivalent.

  3. Option #3: \(2x(x - 5) + 2(x - 5)\) Factoring out \(2(x - 5)\): \[ 2(x - 5)(x + 1) = 2x^2 - 8x - 10 \] This option is also equivalent.

  4. Option #4: \((x - 5)(x - 3)\) Distributing: \[ x^2 - 3x - 5x + 15 = x^2 - 8x + 15 \] This is not equivalent.

  5. Option #5: \(-6x - 10\) This clearly is not equivalent.

Now, the two equivalent options are Option #2 and Option #3.

To arrange them by the lesser number first:

The answer is:

  • Option #2: \((2x + 2)(x - 5)\)
  • Option #3: \(2x(x - 5) + 2(x - 5)\)