Bài 1: tính Cho m=3x²-7x³+5x-9 n=6x³-7x-5x²+16 a, tính M+N b,tính M-N c, N-M <

2 bình luận về “Bài 1: tính Cho m=3x²-7x³+5x-9 n=6x³-7x-5x²+16 a, tính M+N b,tính M-N c, N-M <”

1. a) 

   M + N

   = 3x^2 – 7x^3 + 5x – 9 + 6x^3 – 7x – 5x^2 + 16

   = (3x^2 – 5x^2) + (-7x^3 + 6x^3) + (5x – 7x) + (-9 + 16)

   = -2x^2 – x^3 – 2x + 7

   b) 

   M – N

   = (3x^2 – 7x^3 + 5x – 9) – ( 6x^3 – 7x – 5x^2 + 16)

   =3x^2 – 7x^3 + 5x – 9 – 6x^3 + 7x + 5x^2 – 16

   = (3x^2 + 5x^2) + (-7x^3 – 6x^3) + (5x + 7x) + (-9 – 16)

   = 8x^2 – 13x^3 + 12x – 25

   b) 

   N – M

   = (6x^3 – 7x – 5x^2 + 16) – (3x^2 – 7x^3 + 5x – 9)

   = 6x^3 – 7x – 5x^2 + 16 – 3x^2 + 7x^3 – 5x + 9

   = (6x^3 + 7x^3) + (-7x – 5x) + (-5x^2 – 3x^2) + (16 + 9)

   =  13x^3 – 12x – 8x^2 + 25

   Trả lời
2. a)M+N=3x²-7x³+5x-9+6x³-7x-5x²+16

   ⇔-2x²-x³-2x+7

   b)M-N=3x²-7x³+5x-9-(6x³-7x-5x²+16)

   ⇔3x²-7x³+5x-9-6x³+7x+5x²-16

   ⇔8x²-13x³+12x-25

   c)N-M=6x³-7x-5x²+16-(3x²-7x³+5x-9)

   ⇔6x³-7x-5x²+16-3x²+7x³-5x+9

   ⇔13x³-12x-8x²+25

    

   Trả lời