Question

which expression is equivalent to
$(5a - 1)(3a + 4)$
$\circ\\ 8a^2 + 17a - 4$
$\circ\\ 15a^2 + 23a - 4$
$\circ\\ 15a^2 + 17a - 4$
$\circ\\ 15a^2 + 20a - 4$

Explanation:

Step1: Apply the distributive property (FOIL method)

Multiply the First terms: \(5a \times 3a = 15a^2\)
Multiply the Outer terms: \(5a \times 4 = 20a\)
Multiply the Inner terms: \(-1 \times 3a = -3a\)
Multiply the Last terms: \(-1 \times 4 = -4\)

Step2: Combine like terms

Combine the middle terms: \(20a - 3a = 17a\)
So the expanded form is \(15a^2 + 17a - 4\)

Answer:

\(15a^2 + 17a - 4\) (the third option)