Find the Missing Term in (x+?)(x-8) = x²-5x-24: Binomial Expansion

Question

Complete the missing element

(x+?)(x8)=x25x24 (x+?)(x-8)=x^2-5x-24

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Expand the expression (x+?)(x8)(x+?)(x-8).
  • Step 2: Compare the expanded expression to the given quadratic expression.
  • Step 3: Determine the missing term by matching coefficients.

Now, let's work through each step:

Step 1: Write the left expression as (x+b)(x8)=x28x+bx8b(x+b)(x-8) = x^2 - 8x + bx - 8b.

Step 2: Compare the expanded form, x2+(b8)x8bx^2 + (b-8)x - 8b, to the given x25x24x^2 - 5x - 24.

Step 3: We see that the coefficients for xx should match, so we have b8=5b-8 = -5. Solving for bb, we get:

  • b8=5b=5+8b=3b - 8 = -5 \rightarrow b = -5 + 8 \rightarrow b = 3.

Optionally, verify by comparing the constant terms: 8b=24b=3-8b = -24 \rightarrow b = 3.

Therefore, the missing element in the binomial is 3 \boxed{3} .

Answer

3 3