Question

polynomials: practice
question 2 of 5
select the correct answer.
simplify the following polynomial expression.
$3x(4x + 5) - 4(-x - 3)(2x - 5)$
$\bigcirc\\ 4x^2 + 19x + 15$
$\bigcirc\\ 20x^2 + 19x - 60$
$\bigcirc\\ 4x^2 + 59x + 60$
$\bigcirc\\ 20x^2 + 59x - 15$

Explanation:

Step1: Expand first term

$3x(4x + 5) = 12x^2 + 15x$

Step2: Expand $(-x -3)(2x -5)$

$(-x)(2x) + (-x)(-5) + (-3)(2x) + (-3)(-5) = -2x^2 +5x -6x +15 = -2x^2 -x +15$

Step3: Multiply by -4

$-4(-2x^2 -x +15) = 8x^2 +4x -60$

Step4: Combine all terms

$(12x^2 +15x) + (8x^2 +4x -60) = 20x^2 +19x -60$

Answer:

B. $20x^2 + 19x - 60$