How do you FOIL $(x + 3)(5x - 7)$ ?

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Answer 1 · 2018-05-01T09:28:52

$5x^2+8x-21$

Multiply First $=> x xx 5x = 5x^2$
Multiply Outside $=> x xx -7 = -7x$
Multiply Inside $=> 3 xx 5x = 15x$
Multiply Last $=> 3 xx -7 = -21$

Now collect terms $5x^2-7x+15x-21=5x^2+8x-21$

How do you FOIL (x + 3)(5x - 7)(x + 3)(5x - 7)?