How do you expand $(3x + 1) ( 5x + 7)$ ?

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Answer 1 · 2017-01-30T06:09:36

See the entire solution process below:

To multiply these two terms you multiply each individual term in the left parenthesis by each individual term in the right parenthesis.

$(color(red)(3x) + color(red)(1))(color(blue)(5x) + color(blue)(7))$ becomes:

$(color(red)(3x) xx color(blue)(5x)) + (color(red)(3x) xx color(blue)(7)) + (color(red)(1) xx color(blue)(5x)) + (color(red)(1) xx color(blue)(7))$

$15x^2 + 21x + 5x + 7$

We can now combine like terms:

$15x^2 + (21 + 5)x + 7$

$15x^2 + 26x + 7$

How do you expand (3x + 1) ( 5x + 7)(3x + 1) ( 5x + 7)?