Question

Choose the correct simplification of (4x^3 y^4 z^5)(5x^4 y^5 z^3).

20x^12 y^20 z^15
9x^7 y^9 z^8
9x^12 y^20 z^15
20x^7 y^9 z^8

Answer 1

(4x^3 y^4 z^5)(5x^4 y^5 z)

4*5 = 20, and

x^3*x^4 = x*7, and

y^4*y^5 = y^9, and, finally,

z^5*z^3 = z^8

So, stringing these four results together via multiplication, we get:

20*x^7*y^9*z^8 (answer)

Answer 2

Your answer is the last option,

`20 {x}^(7) {y}^(9) {z}^(8)`
This is because when you multiply powers, you add them, so 4x³ × 5x⁴ = 20x^7, and since the last option is the only one with 20x^7, that is the answer.
I hope this helps!