Question 187300


{{{(a-1)(a+3)}}} Start with the given expression.



Now let's FOIL the expression.



Remember, when you FOIL an expression, you follow this procedure:



{{{(highlight(a)-1)(highlight(a)+3)}}} Multiply the <font color="red">F</font>irst terms:{{{(a)*(a)=a^2}}}.



{{{(highlight(a)-1)(a+highlight(3))}}} Multiply the <font color="red">O</font>uter terms:{{{(a)*(3)=3*a}}}.



{{{(a+highlight(-1))(highlight(a)+3)}}} Multiply the <font color="red">I</font>nner terms:{{{(-1)*(a)=-a}}}.



{{{(a+highlight(-1))(a+highlight(3))}}} Multiply the <font color="red">L</font>ast terms:{{{(-1)*(3)=-3}}}.



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So we have the terms: {{{a^2}}}, {{{3*a}}}, {{{-a}}}, {{{-3}}} 



{{{a^2+3*a-a-3}}} Now add every term listed above to make a single expression.



{{{a^2+2*a-3}}} Now combine like terms.



So {{{(a-1)(a+3)}}} FOILs to {{{a^2+2*a-3}}}.



In other words, {{{(a-1)(a+3)=a^2+2*a-3}}}.