Question 1156796
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....., Expanding each integer in the expression 21 × 12, the result is [(2 × 101) + (1 × 100)] × [(1 × 101) + (2 × 100)]. Replace the 10s with x’s and then multiply this expression using FOIL. Compare it with the normal integer multiplication method used above: How are they similar? Show your work.
- i do not understand what they mean to replace the 10s with x's.
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Use x in place of 10 to show "place value".

{{{21*12}}}

{{{(20+1)(10+2)}}}

{{{(2*10+1)(1*10+2)}}}

Replacing with x,

{{{(2x+1)(x+2)}}}

and then you can do the intended FOIL multiplication.