Question

3. [8.01] Factor completely: 42x3y4 − 63x2y (4 points)
21x2y(2xy3 − 3)
21x2(2xy4 − 3y)
x2y(42xy3 − 63)
21x(2x2y4 − 3xy)

Answer 1

find common factors of 42 and 63.... looks a bit like 21

\[21(2x^3y^4 - 3x^2y)\]

now identify further common factors

perhaps

\[x^2y\]

will give

\[21x^2y(2xy^2 - 3)\]

Answer 2

oops

\[21x^2y(2xy^3 - 3)\]