372.
1→ a ;
2→(a- a*15/100) =0,85a.
3 →a + 85a - 40 .
(1→) +(2→)+(3→) =a+(0,85a)+(a+0,85a -40) =3,7a -40 .
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373 .
б) = -x² -x +4 -3x -4 +x² -1 =- 4x -1.
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г) = 12ab -a²-11ab -a² +ab -6,2a² = -8,2a² +2ab .
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375.
б) = 4x +(2x-1) -(x-4)+1 = 4x +2x-1 -x+4+1 =5x +4.
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376.
б) A-B +C = (x²-2xy +y²) -(2x² -y²) +(x² -3xy) =
x²-2xy +y² -2x² +y² +x² -3xy = 2y²-5xy.
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377.
б) (a³ -b² -c) -(3a³ -2b²+c)+(2a³ -b²+2c) и 0.
(a³ -b² -c) -(3a³ -2b²+c)+(2a³ -b²+2c)=a³ - b² - c - 3a³ +2b²-c+2a³ -b²+2c =0 .