How do you find the product of $(9b+1)(5b+2)$ using FOIL?

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Answer 1 · 2016-05-02T20:58:32

$(9b+1)(5b+2)=45b^2+23b+2$

FOIL = First + Outside + Inside + Last

is a useful mnemonic to help remember all of the combinations of terms you need to combine when multiplying two binomials.

$(9b+1)(5b+2)=overbrace((9b*5b))^"First" + overbrace((9b*2))^"Outside" + overbrace((1*5b))^"Inside" + overbrace((1*2))^"Last"$

$=45b^2+18b+5b+2$

$=45b^2+23b+2$

How do you find the product of (9b+1)(5b+2)(9b+1)(5b+2) using FOIL?