Perform the operation(s) and simplify completely. −(2x+6)(3x+4)+5x^2−7x

1 answer

Let's simplify the expression step by step:

We start with the expression:

\[ -(2x + 6)(3x + 4) + 5x^2 - 7x \]

First, we need to expand \(-(2x + 6)(3x + 4)\):

\[ (2x + 6)(3x + 4) = 2x \cdot 3x + 2x \cdot 4 + 6 \cdot 3x + 6 \cdot 4 \]

Calculating each term:

  • \(2x \cdot 3x = 6x^2\)
  • \(2x \cdot 4 = 8x\)
  • \(6 \cdot 3x = 18x\)
  • \(6 \cdot 4 = 24\)

Now, combine these results:

\[ (2x + 6)(3x + 4) = 6x^2 + 8x + 18x + 24 = 6x^2 + 26x + 24 \]

Now, apply the negative sign:

\[ -(2x + 6)(3x + 4) = -6x^2 - 26x - 24 \]

Next, we combine this with the rest of the expression:

\[ -6x^2 - 26x - 24 + 5x^2 - 7x \]

Combine like terms:

  1. For \(x^2\) terms: \(-6x^2 + 5x^2 = -x^2\)

  2. For \(x\) terms: \(-26x - 7x = -33x\)

  3. The constant term is: \(-24\)

Putting it all together gives:

\[ -x^2 - 33x - 24 \]

So, the fully simplified expression is:

\[ \boxed{-x^2 - 33x - 24} \]