Question 114200
{{{(3x+0.4)(3x-0.4)}}} Start with the given expression


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



Multiply the First terms:{{{(3x)*(3x)=9x^2}}}



Multiply the Outer terms:{{{(3x)*(-0.4)=-1.2x}}}



Multiply the Inner terms:{{{(0.4)*(3x)=1.2x}}}



Multiply the Last terms:{{{(0.4)*(-0.4)=-0.16}}}



{{{9x^2-1.2x+1.2x-0.16}}} Now collect every term to make a single expression




{{{9x^2-0.16}}} Now combine like terms



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Answer:

So {{{(3x+0.4)(3x-0.4)}}} foils and simplifies to  {{{9x^2-0.16}}}


In other words, {{{(3x+0.4)(3x-0.4)=9x^2-0.16}}}


Notice how  {{{9x^2-0.16}}} factors back to the original expression {{{(3x+0.4)(3x-0.4)}}}. So this verifies our answer.