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1) a)
=\(\left(4-1+8\right)x^2=11x^2\)
b) =\(\left(\dfrac{1}{2}-\dfrac{3}{4}+1\right)x^2y^2=\dfrac{3}{4}x^2y^2\)
c) =(3-7+4-6)y=5y 2) a) ...=\(\left[\left(\dfrac{-2}{3}y^3\right)-\dfrac{1}{2}y^3\right]+3y^2-y^2\\ =\left[\left(\dfrac{-2}{3}-\dfrac{1}{2}\right)y^3\right]+\left(3-1\right)y^2=\dfrac{-7}{6}y^3+2y^2\) b) ...=\(\left(5x^3-x^3\right)-\left(3x^2+4x^2\right)+\left(x-x\right)=4x^3-7x^2\) 3) a)A=\(\left(5.\dfrac{1}{2}\right).\left(x.x^2.x\right)\left(y^2.y^2\right)=\dfrac{5}{2}x^4y^4\) b)Vậy Đơn thức A có bậc 8; hệ số là \(\dfrac{5}{2}\); phần biến là \(x^4y^4\) c)Khi x=1;y=-1 thì A=\(\dfrac{5}{2}.1^4.\left(-1\right)^4=\dfrac{5}{2}\)
bài 1
a) \(-\frac{1}{3}xy\).(3\(x^2yz^2\))
=\(\left(-\frac{1}{3}.3\right)\).\(\left(x.x^2\right)\).(y.y).\(z^2\)
=\(-x^3\).\(y^2z^2\)
b)-54\(y^2\).b.x
=(-54.b).\(y^2x\)
=-54b\(y^2x\)
c) -2.\(x^2y.\left(\frac{1}{2}\right)^2.x.\left(y^2.x\right)^3\)
=\(-2x^2y.\frac{1}{4}.x.y^6.x^3\)
=\(\left(-2.\frac{1}{4}\right).\left(x^2.x.x^3\right).\left(y.y^2\right)\)
=\(\frac{-1}{2}x^6y^3\)
Bài 3:
a) \(f\left(x\right)=-15x^2+5x^4-4x^2+8x^2-9x^3-x^4+15-7x^3\)
\(f\left(x\right)=\left(5x^4-x^4\right)-\left(9x^3+7x^3\right)-\left(15x^2+4x^2-8x^2\right)+15\)
\(f\left(x\right)=4x^4-16x^3-11x^2+15\)
b)
\(f\left(x\right)=4x^4-16x^3-11x^2+15\)
\(f\left(1\right)=4\cdot1^4-16\cdot1^3-11\cdot1^2+15\)
\(f\left(1\right)=4\cdot1^4-16\cdot1^3-11\cdot1^2+15\)
\(f\left(1\right)=-8\)
\(f\left(x\right)=4x^4-16x^3-11x^2+15\)
\(f\left(-1\right)=4\cdot\left(-1\right)^4-16\cdot\left(-1\right)^3-11\cdot\left(-1\right)^2+15\)
\(f\left(-1\right)=24\)
Không chắc nữa chắc sai -.-
a) \(A=\frac{3}{2}\left(-x^2y^3\right)^2\left(-x\right)^2\)
\(=\frac{3}{2}.[\left(-x\right)^{2^2}.\left(-x\right)^2].y^{3^2}\)
\(=\frac{3}{2}.\left[\left(-x\right)^4.\left(-x^2\right)\right].y^6\)
\(=\frac{3}{2}.x^6.y^6\)
b) A.B
\(\)\((\frac{3}{2}.x^6.y^6).x^6y^6\)
\(=\frac{3}{2}.\left(x^6.x^6\right).\left(y^6.y^6\right)\)
\(=\frac{3}{2}.x^{12}.y^{12}\)
A + B
\((\frac{3}{2}.x^6.y^6)+\left(x^6y^6\right)\)
\(=\frac{3}{2}.\left(x^6.x^6\right)+\left(y^6.y^6\right)\)
\(=\frac{3}{2}.x^{12}+y^{12}\)
2) P-Q
\(\left(4x^2-5xy+3x-4\right)-(y^2+4+5xy-2y+x)\)
\(=4x^2-5xy-3x-4-y^2+4x^2+5xy-2y+x\)
\(=\left(4x^2-4x^2\right)+\left(5xy-5xy\right)+\left(3x-x\right)+4-y\)
\(=2x+4-y\)
b) Không biết làm :v