(6+b)×(6+b)=(6+b)²=36+12b+b².
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(t+m)²=t²+2tm+m²=t²+2mt+m².
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(t-3)²=t²-2t*3+3²=t²-6t+9.
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(2t+1)²=(2t)²+2*3t*1+1²=4t²+4t+1.
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