(3m+2n)(7m-6n)

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(3m+2n)(7m-6n)
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(3m+2n)(7m-6n)
(3m+2n)(7m-6n)

(3m+2n)(7m-6n)
原式=3m(7m-6n)+2n(7m-6n)
=21m²-18mn+14mn-12n²
=21m²-4mn-12n²

3X+Y=K+1 (1)
X+4Y=3 (2)
(1)*5-(2)*4
15X+5Y-4X-16Y=5K+5-12
11X-11Y=5K-7
210<5K<20
3<5K-7<13
所以3<11X-11Y<13
3/11X+4Y=3 (2)
(1...

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3X+Y=K+1 (1)
X+4Y=3 (2)
(1)*5-(2)*4
15X+5Y-4X-16Y=5K+5-12
11X-11Y=5K-7
210<5K<20
3<5K-7<13
所以3<11X-11Y<13
3/11X+4Y=3 (2)
(1)*5-(2)*4
15X+5Y-4X-16Y=5K+5-12
11X-11Y=5K-7
210<5K<20
3<5K-7<13
所以3<11X-11Y<13
3/11

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