Find the product: (7x + 2y) × (x + 4y)
Question:

Find the product:
(7x + 2y) × (x + 4y)

Solution:

By horizontal method:

$(7 x+2 y) \times(x+4 y)$

$=7 x(x+4 y)+2 y(x+4 y)$

$=7 x^{2}+28 x y+2 x y+8 y^{2}$

$=7 x^{2}+30 x y+8 y^{2}$