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Ta có: P(x)+Q(x)= x2y-2xy2+5xy+3+3xy2+5x2y-7xy+2=6x2y+xy2-2xy+5
A + B + C = ( 4x2 - 5xy + 3y2 ) + ( 3x2 + 2xy + y2 ) + ( -x2 + 3xy + 2y2 )
= 4x2 - 5xy + 3y2 + 3x2 + 2xy + y2 - x2 + 3xy + 2y2
= ( 4x2 - 3x2 - x2 ) + ( 5xy + 2xy + 3xy ) + ( 3y2 + y2 + 2y2 )
= 10xy + 6y2
B - C - A = ( 3x2 + 2xy + y2 ) - ( -x2 + 3xy + 2y2 ) - ( 4x2 - 5xy + 3y2 )
= 3x2 + 2xy + y2 + x2 - 3xy - 2y2 - 4x2 + 5xy - 3y2
= ( 3x2 + x2 - 4x2 ) - ( 2xy - 3xy + 5xy ) - ( y2 - 2y2 - 3y2 )
= 0 - 0 - ( -4y2 )
= 0 + 4y2
= 4y2
C - A - B = ( -x2 + 3xy + 2y2 ) - ( 4x2 - 5xy + 3y2 ) - ( 3x2 + 2xy + y2 )
= -x2 + 3xy + 2y2 - 4x2 + 5xy - 3y2 - 3x2 - 2xy - y2
= ( -x2 - 4x2 - 3x2 ) - ( 3xy + 5xy - 2xy ) - ( 2y2 - 3y2 - y2 )
= -8x2 - 6xy - ( -2y2 )
= -8x2 - 6xy + 2y2
* Lần đầu làm xD Sai sót gì mong bạn thông cảm *
C= x2 y - \(\dfrac{1}{2}\)xy2 + \(\dfrac{1}{3}\)x2y +\(\dfrac{2}{3}\)xy2 + 1
C=(x2y + \(\dfrac{1}{3}\)x2y )+( - \(\dfrac{1}{2}\)xy2 +\(\dfrac{2}{3}\)xy2)+ 1
C=\(\dfrac{4}{3}\)x2y +\(\dfrac{1}{6}\)xy2+1
=>Bặc: 3
D= xy2z + 3xyz2 - \(\dfrac{1}{5}\)xy2z - \(\dfrac{1}{3}\)xyz2 - 2
D=(xy2z - \(\dfrac{1}{5}\)xy2z )+( 3xyz2 - \(\dfrac{1}{3}\)xyz2) - 2
D=\(\dfrac{4}{5}\)xy2z +\(\dfrac{8}{3}\)xyz2 - 2
=> Bậc :4
E = 3xy5 - x2y + 7xy - 3xy5 + 3x2y - \(\dfrac{1}{2}\)xy + 1
E=(3xy5- 3xy5) + (- x2y + 3x2y) + (7xy - \(\dfrac{1}{2}\)xy)+ 1
E= 2x2y + \(\dfrac{13}{2}\)xy + 1
=> Bậc: 3
K = 5x3 - 4x + 7x2 - 6x3 + 4x + 1
K= (5x3 - 6x3 ) + (- 4x + 4x) +1
K= -1x3 + 1
=>Bậc: 3
F = 12x3y2 - \(\dfrac{3}{7}\)x4y2 + 2xy3 - x3y2 + x4y2 - xy3 - 5
F=( 12x3y2 - x3y2) + (- \(\dfrac{3}{7}\)x4y2 + x4y2) + (2xy3 - xy3) -5
F=11x3y2 + \(\dfrac{4}{7}\)x4y2 + xy3 - 5
=> Bậc :6
CHÚC BN HỌC TỐT ^-^
Bài 26:
\(A+B+C=4x^2-5xy+3y^2+3x^2+2xy+y^2-x^2+3xy+2y^2\)
\(=\left(4x^2+3x^2-x^2\right)+\left(-5xy+2xy+3xy\right)+\left(3y^2+y^2+2y^2\right)\)
\(=6x^2+6y^2\)
\(B-C-A=\left(3x^2+2xy+y^2\right)-\left(-x^2+3xy+2y^2\right)-\left(4x^2-5xy+3y^2\right)\)
\(=3x^2+2xy+y^2+x^2-3xy-2y^2-4x^2+5xy-3y^2\)
\(=\left(3x^2-4x^2+x^2\right)+\left(2xy-3xy+5xy\right)+\left(y^2-2y^2-3y^2\right)\)
\(=-4xy-2y^2\)
\(C-A-B=\left(-x^2+3xy+2y^2\right)-\left(4x^2-5xy+3y^2\right)-\left(3x^2+2xy+y^2\right)\)
\(=-x^2+3xy+2y^2-4x^2+5xy-3y^2-3x^2-2xy-y^2\)
\(=\left(-x^2-4x^2-3x^2\right)+\left(3xy+5xy-2xy\right)+\left(2y^2-3y^2-y^2\right)\)
\(=-8x^2+6xy-2y^2\)
cái câu B-C-A ý thì kết quả phải là 4xy-4y^2 chứ
vì: 2xy-3xy+5xy =4 xy
y^2 - 2y^2-3y^2 = -4y^2
=> = 4xy-4y^2
Bài 1 :
A + B = 4x2 - 5xy + 3y2 + 3x2 + 2xy - y2
= ( 4x2 + 3x2 ) - ( 5xy - 2xy ) + ( 3y2 - y2 )
= 7x2 - 3xy + 2y2
A - B = 4x2 - 5xy + 3y2 - ( 3x2 + 2xy - y2 )
= 4x2 - 5xy + 3y2 - 3x2 - 2xy + y2
= ( 4x2 - 3x2 ) - ( 5xy + 2xy ) + ( 3y2 + y2 )
= x2 - 7xy + 4y2
Bài 2 :
a) M + (5x2 - 2xy) = 6x2 + 9xy - y2
M = 6x2 + 9xy - y2 - (5x2 - 2xy)
M = 6x2 + 9xy - y2 - 5x2 + 2xy
M = ( 6x2 - 5x2 ) + ( 9xy + 2xy ) - y2
M = x2 + 11xy - y2
Vậy M = x2 + 11xy - y2
b) (3xy - 4y2) - N = x2 - 7xy + 8y2
N = 3xy - 4y2 - x2 - 7xy + 8y2
N = ( 3xy - 7xy ) - ( 4y2 - 8y2 ) - x2
N = -4xy + 4y2 - x2
Vậy N = -4xy + 4y2 - x2
3, Cho đa thức
A(x)+B(x) = (3x4-\(\dfrac{3}{4}\)x3+2x2-3)+(8x4+\(\dfrac{1}{5}\)x3-9x+\(\dfrac{2}{5}\))
= 3x4-\(\dfrac{3}{4}\)x3+2x2-3+8x4+\(\dfrac{1}{5}\)x3-9x+\(\dfrac{2}{5}\)
= (3x4+8x4)+(-3/4x3+1/5x3)+(-3+2/5)+2x2-9x
= 11x4 -0.55x3-2.6+2x2-9x
A(x)-B(x)=(3x4-\(\dfrac{3}{4}\)x3+2x2-3)-(8x4+\(\dfrac{1}{5}\)x3-9x+\(\dfrac{2}{5}\))
= 3x4-\(\dfrac{3}{4}\)x3+2x2-3-8x4-\(\dfrac{1}{5}\)x3+9x-\(\dfrac{2}{5}\)
= (3x4-8x4)+(-3/4x3-1/5x3)+(-3-2/5)+2x2+9x
= -5x4-0.95x3-3.4+2x2+9x
B(x)-A(x)=(8x4+\(\dfrac{1}{5}\)x3-9x+\(\dfrac{2}{5}\))-(3x4-\(\dfrac{3}{4}\)x3+2x2-3)
=8x4+\(\dfrac{1}{5}\)x3-9x+\(\dfrac{2}{5}\)-3x4+\(\dfrac{3}{4}\)x3-2x2+3
=(8x4-3x4)+(1/5x3+3/4x3)+(2/5+3)-9x-2x2
= 5x4+0.95x3+2.6-9x-2x2
a, \(4x^2y^2z\left(-3xy^3z\right)=-12x^3y^5z^2\)
b, \(\left(-6x^2yz\right)\left(-\frac{4}{3}x^2yz^3\right)=8x^4y^2z^4\)
a,\(\left(3x^2.y^2\right).\left(-2xy^2\right)\)
\(=\left(-6\right).x^3.y^4\)
Hok tốt
=(3x^2+7xy-11xy+5x^2)+(4x^2yz^3-3xy^2+x^2yt^3+5xy^2)
=3x^2+7xy-11xy+5x^2+4x^2yz^3-3xy^2yt^3+5xy^2
=(3x^2+5x^2)+(7xy-11xy)+(-3xy^2+5xy^2)+4x^2yz^3+x^2yt^3
=8x^2-4xy+2xy^2+4x^2yz^3+^2yt^3
cho mik nha
a)3x2+7xy-11xy+5x2=(3x2+5x2)+(7xy-11xy)=8x2+(-4xy)
b)4x2yz3-3xy2+x2yt3+5xy2=4x2yz3+(-3xy2+5xy2)+x2yt3=4x2yz3+2xy2+x2yt3
Chúc bạn học tốt !!!!