To determine which of the provided expressions are equivalent to the expression \((4−2z^2−z)(3z+5)\), we first need to fully expand the original expression.
Let's expand \((4 - 2z^2 - z)(3z + 5)\):
-
Distribute \(3z\): \[ 3z(4) + 3z(-2z^2) + 3z(-z) = 12z - 6z^3 - 3z^2 \]
-
Distribute \(5\): \[ 5(4) + 5(-2z^2) + 5(-z) = 20 - 10z^2 - 5z \]
-
Now combine all these results: \[ (12z - 6z^3 - 3z^2) + (20 - 10z^2 - 5z) = -6z^3 + (12z - 5z) + (-3z^2 - 10z^2) + 20 \] \[ = -6z^3 + 7z - 13z^2 + 20 \] Rearranging this, we get: \[ -6z^3 - 13z^2 + 7z + 20 \]
Now, we can compare this final expression with the options provided in your question. We are looking for expressions that match \(-6z^3 - 13z^2 + 7z + 20\).
-
Expression 1: \(6z^3−10z^2+5z+12z+20−3z^2\) simplifies to: \[ 6z^3 − (10z^2 + 3z^2) + (5z + 12z) + 20 = 6z^3 - 13z^2 + 17z + 20 \quad (\text{not equivalent}) \]
-
Expression 2: \(-6z^3−13z^2+7z+20\) matches our result.
-
Expression 3: \(-6z^3−7z^2−2z+20\) does not match the coefficients.
-
Expression 4: \(-6z^3−10z^2−3z^2−5z+12z+20\) simplifies to: \[ -6z^3 − (10z^2 + 3z^2) + (12z - 5z) + 20 = -6z^3 - 13z^2 + 7z + 20 \quad (\text{this is equivalent}) \]
-
Expression 5: \(-6z^3−13z^2−5z+12z+20\) simplifies to: \[ -6z^3 - 13z^2 + (12z - 5z) + 20 = -6z^3 − 13z^2 + 7z + 20 \quad (\text{this is equivalent}) \]
Based on this analysis, the equivalent expressions for \((4−2z^2−z)(3z+5)\) are:
- \(-6z^3−13z^2+7z+20\) (Expression 2)
- \(-6z^3−10z^2−3z^2−5z+12z+20\) (Expression 4)
- \(-6z^3−13z^2−5z+12z+20\) (Expression 5)
Thus, the selected equivalent expressions are Expression 2, Expression 4, and Expression 5.