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a) P + (x2 – 2y2) = x2 – y2 + 3y2 – 1
P = (x2 – y2 + 3y2 – 1) - (x2 – 2y2)
P = x2 – y2 + 3y2 – 1 - x2 + 2y2
P = x2 – x2 – y2 + 3y2 + 2y2 – 1
P = 4y2 – 1.
Vậy P = 4y2 – 1.
b) Q – (5x2 – xyz) = xy + 2x2 – 3xyz + 5
Q = (xy + 2x2 – 3xyz + 5) + (5x2 – xyz)
Q = xy + 2x2 – 3xyz + 5 + 5x2 – xyz
Q = 7x2 – 4xyz + xy + 5
Vậy Q = 7x2 – 4xyz + xy + 5.
a) P + (x2 – 2y2) = x2 – y2 + 3y2 – 1
P = (x2 – y2 + 3y2 – 1) - (x2 – 2y2)
P = x2 – y2 + 3y2 – 1 - x2 + 2y2
P = x2 – x2 – y2 + 3y2 + 2y2 – 1
P = 4y2 – 1.
Vậy P = 4y2 – 1.
b) Q – (5x2 – xyz) = xy + 2x2 – 3xyz + 5
Q = (xy + 2x2 – 3xyz + 5) + (5x2 – xyz)
Q = xy + 2x2 – 3xyz + 5 + 5x2 – xyz
Q = 7x2 – 4xyz + xy + 5
Vậy Q = 7x2 – 4xyz + xy + 5.
a) P+(x2-2y2)= x2-y2+3y2-1
P =(x2-y+3y2-1)-(x2-2y2)
= x2-y+3y2-1-x2+2y2
=(x2-x2)-(y-3y2-2y2)-1
= -4y2-1
b) Q-(5x2-xyz) = xy+2x2-3xyz+5
Q =(xy+2x2-3xyz+5)+(5x2-xyz)
=xy+2x2-3xyz+5+5x2-xyz
=(2x2+5x2)-(3xyz+xyz)+xy+5
=7x2-4xyz+xy+5
Có làm sai mong bạn thông cảm cho!
A = 1/4x2y . 2x3y2 . 3x5y
= (1/4 . 2 . 3) . x2y . x3y2 . x5y
= 3/2x10y4 có bậc là: 10
B = x2y5 - 3xyz - x2y5 + xyz + x4
= (1 . 3 . 1 . 1 . 1) . x2y5 . xyz . x2y5 . xyz . x4
= 3x10y12z2 có bậc là : 12
a)
A= -7x2 - 3y2 + 9xy - 2x2 + y2
= (-7x2 - 2x2) + (-3y2 + y2) + 9xy
= -9x2 - 2y2 + 9xy
B= 5x2 + xy - x2 - 2y2
= (5x2 - x2) - 2y2 + xy
= 4x2 - 2y2 + xy
b)
C= A +B = (-9x2 - 2y2 + 9xy) + (4x2 - 2y2 + xy)
= -9x2 - 2y2 + 9xy + 4x2 -2y2 + xy
= (-9x2 + 4x2) + (-2y2 -2y2) + (9xy + xy)
C = -5x2 -4y2 +10xy
a) \(A=-7x^2-3y^2+9xy-2x^2+y^2\)
\(\Leftrightarrow A=\left(-7x^2-2x^2\right)-\left(3y^2-y^2\right)+9xy\)
\(\Leftrightarrow A=-9x^2-2y^2+9xy\)
\(B=5x^2+xy-x^2-2y^2\)
\(\Leftrightarrow B=\left(5x^2-x^2\right)-2y^2+xy\)
\(\Leftrightarrow B=4x^2-2y^2+xy\)
b) \(C=A+B\)
\(\Leftrightarrow C=-9x^2-2y^2+9xy+4x^2-2y^2+xy\)
\(\Leftrightarrow C=\left(-9x^2+4x^2\right)-\left(2y^2+2y^2\right)+\left(9xy+xy\right)\)
\(\Leftrightarrow C=-5x^2-4y^2+10xy\)
P=4y2-1
Q=xy+7y2-4xyz+5