Algebra · real student question

Divide the polynomial by the monomial: (20x^2y^2 + 16x^2y - 12xy^2) divided by 4xy. Check the answer by showing that the product of the divisor and the quotient is the dividend.

Question

Divide the polynomial by the monomial. Check the answer by showing that the product of the divisor and the quotient is the dividend.

20x2y2+16x2y12xy24xy\frac{20x^{2}y^{2}+16x^{2}y-12xy^{2}}{4xy}

Step-by-step solution

  1. Split the single fraction into one fraction per term. Division distributes over addition in the numerator (though never over the denominator):

    20x2y24xy+16x2y4xy12xy24xy.\frac{20x^{2}y^{2}}{4xy}+\frac{16x^{2}y}{4xy}-\frac{12xy^{2}}{4xy}.

  2. Divide the first term. Handle the coefficient and each variable separately, subtracting exponents:

    204=5,x2x=x,y2y=y  5xy.\frac{20}{4}=5,\qquad \frac{x^{2}}{x}=x,\qquad \frac{y^{2}}{y}=y\ \Longrightarrow\ 5xy.

  3. Divide the second term. Here the yy powers cancel completely, leaving y0=1y^{0}=1:

    164=4,x2x=x,yy=1  4x.\frac{16}{4}=4,\qquad \frac{x^{2}}{x}=x,\qquad \frac{y}{y}=1\ \Longrightarrow\ 4x.

  4. Divide the third term, keeping its sign. The xx powers cancel this time:

    124=3,xx=1,y2y=y  3y.\frac{-12}{4}=-3,\qquad \frac{x}{x}=1,\qquad \frac{y^{2}}{y}=y\ \Longrightarrow\ -3y.

  5. Assemble the quotient.

    5xy+4x3y.5xy+4x-3y.

  6. Carry out the requested check. Multiply the divisor by the quotient:

    4xy(5xy+4x3y)=20x2y2+16x2y12xy2,4xy\left(5xy+4x-3y\right)=20x^{2}y^{2}+16x^{2}y-12xy^{2},

    which is exactly the dividend, so the division is correct (for x0x\neq 0, y0y\neq 0).

Answer

5xy+4x3y5xy+4x-3y

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