Algebra · real student question

Split (4x¹⁰ − 5x⁹ − 20x⁴)/(4x²) into separate fractions and simplify.

Question

Split into separate fractions and simplify:

4x105x920x44x2\frac{4x^{10}-5x^{9}-20x^{4}}{4x^{2}}

Step-by-step solution

  1. Split the single fraction into three. A sum in the numerator can always be divided term by term — this is the distributive law for division, a+b+cd=ad+bd+cd\tfrac{a+b+c}{d}=\tfrac ad+\tfrac bd+\tfrac cd. (The same is not true for a sum in the denominator, which is the usual confusion.)

    4x104x25x94x220x44x2\frac{4x^{10}}{4x^{2}}-\frac{5x^{9}}{4x^{2}}-\frac{20x^{4}}{4x^{2}}

  2. Simplify the first term. Divide coefficients and subtract exponents:

    4x104x2=1x102=x8\frac{4x^{10}}{4x^{2}}=1\cdot x^{10-2}=x^{8}

  3. Simplify the second term. Here 55 does not divide evenly by 44, so a fraction survives:

    5x94x2=54x7\frac{5x^{9}}{4x^{2}}=\frac54x^{7}

  4. Simplify the third term.

    20x44x2=5x2\frac{20x^{4}}{4x^{2}}=5x^{2}

  5. Reassemble with the original signs.

    x854x75x2(x0)\boxed{x^{8}-\frac54x^{7}-5x^{2}}\qquad(x\neq 0)

  6. Check by multiplying back. 4x2(x854x75x2)=4x105x920x44x^{2}\left(x^{8}-\tfrac54x^{7}-5x^{2}\right)=4x^{10}-5x^{9}-20x^{4} ✓, which is the original numerator. A quick numerical check at x=1x=1: the original is 45204=214=5.25\tfrac{4-5-20}{4}=-\tfrac{21}{4}=-5.25, and the answer gives 11.255=5.251-1.25-5=-5.25 ✓.

Answer

x854x75x2(x0)x^{8}-\dfrac54x^{7}-5x^{2}\qquad(x\neq 0)

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