Which of the following are the partial products for $\left(3 c^2+2 d\right)\left(-5 c^2+d\right)$? Choose four correct answers.


  • $-15 c^2$
  • $-15 c^4$
  • $3 c d^3$
  • $3 c^2 d$
  • $-10 c^2 d$
  • $2 d^2$

Verified Answer :

  • Use the FOIL method to expand the binomial expression \((3c^2 + 2d)(-5c^2 + d)\).
  • Calculate the product of each pair of terms: First \(-15c^4\), Outer \(3c^2d\), Inner \(-10c^2d\), and Last \(2d^2\).
  • Match these four results against the given options.
  • The correct partial products are \(-15c^4\), \(3c^2d\), \(-10c^2d\), and \(2d^2\). \(\boxed{{-15c^4, 3c^2d, -10c^2d, 2d^2}}\).

Explanation

  1. Analyzing the Problem and FOIL Method

To find the partial products of the expression \((3c^2 + 2d)(-5c^2 + d)\), we utilize the distributive property, commonly referred to as the FOIL method for binomial multiplication. The FOIL method allows us to multiply each term in the first binomial by each term in the second binomial. The formula for the expansion of \((a + b)(x + y)\) is given by \(ax + ay + bx + by\). In our specific expression, we have \(a = 3c^2\), \(b = 2d\), \(x = -5c^2\), and \(y = d\).

  1. Calculating the Partial Products

Applying the FOIL steps systematically:

  • First: Multiply the first terms of each binomial: \((3c^2) \times (-5c^2) = -15c^4\).
  • Outer: Multiply the outer terms of each binomial: \((3c^2) \times (d) = 3c^2d\).
  • Inner: Multiply the inner terms of each binomial: \((2d) \times (-5c^2) = -10c^2d\).
  • Last: Multiply the last terms of each binomial: \((2d) \times (d) = 2d^2\).
  1. Identifying Correct Answers

Comparing our results \(-15c^4\), \(3c^2d\), \(-10c^2d\), and \(2d^2\) with the provided options, we find that these four values match exactly with four of the choices given. Therefore, the correct partial products are \(-15c^4\), \(3c^2d\), \(-10c^2d\), and \(2d^2\).

Examples

In real-world engineering or physics, such as calculating the area of a rectangle whose dimensions are changing, you might encounter expressions involving variables like \((3w^2 + 2h)(-5w^2 + h)\). Expanding these expressions is a fundamental skill for simplifying physical models, determining net forces, or calculating areas and volumes in geometry. By breaking down the product into its partial components, you can more easily analyze how each variable contributes to the final outcome.