What expression is equivalent to $\left(5 z^2+3 z+2\right)^2$ ?


A$5 z^4+3 z^2+4$
B$5 z^4+9 z^2+4$
C$25 z^4+30 z^3+19 z^2+12 z+4$
D$25 z^4+30 z^3+29 z^2+12 z+4$

Verified Answer :

  • Identify the trinomial square formula \((a+b+c)^2 = a^2+b^2+c^2+2ab+2bc+2ac\).
  • Substitute \(a=5z^2\), \(b=3z\), and \(c=2\) into the formula.
  • Calculate all squared terms and cross-products.
  • Combine like terms to get the final expanded expression \(\boxed{25 z^4+30 z^3+29 z^2+12 z+4}\).

Explanation

  1. Identifying the Trinomial Square Formula

We are asked to expand the algebraic expression \((5z^2 + 3z + 2)^2\). This is the square of a trinomial. The general formula for the square of a trinomial is:
\[(a + b + c)^2 = a^2 + b^2 + c^2 + 2ab + 2bc + 2ac\]
where \(a\), \(b\), and \(c\) are the individual terms of the trinomial. In our case, we have \(a = 5z^2\), \(b = 3z\), and \(c = 2\).

  1. Calculating Individual Squared Terms and Cross-Terms

Now, let's calculate the individual squared terms:

  • \(a^2 = (5z^2)^2 = 25z^4\)
  • \(b^2 = (3z)^2 = 9z^2\)
  • \(c^2 = (2)^2 = 4\)

Next, we calculate the double products (cross-terms):

  • \(2ab = 2(5z^2)(3z) = 30z^3\)
  • \(2bc = 2(3z)(2) = 12z\)
  • \(2ac = 2(5z^2)(2) = 20z^2\)
  1. Combining and Simplifying Terms

Now, we combine all these terms to get the expanded expression:
\[(5z^2 + 3z + 2)^2 = 25z^4 + 9z^2 + 4 + 30z^3 + 12z + 20z^2\]
To simplify, we group the like terms (the terms with \(z^2\)):
\[25z^4 + 30z^3 + (9z^2 + 20z^2) + 12z + 4\]
\[= 25z^4 + 30z^3 + 29z^2 + 12z + 4\]
Comparing this result to the given options, we see it matches the final option.

Examples

Expanding trinomials like \((5z^2 + 3z + 2)^2\) is a fundamental skill in algebra, useful for simplifying complex physics equations or engineering models. For instance, if you are modeling the trajectory of a projectile where the height is defined by a polynomial, squaring that expression is a common step to calculate potential energy or other related physical properties. This algebraic manipulation ensures you can accurately analyze and simplify complex systems in science and technology.