Algebra · real student question

Simplify sqrt(48x^12) / sqrt(2x) using the quotient rule for square roots, assuming x > 0.

Question

Simplify using the quotient rule for square roots. Assume that x>0x>0.

48x122x\frac{\sqrt{48x^{12}}}{\sqrt{2x}}

Step-by-step solution

  1. Merge the two radicals before simplifying either one. The quotient rule reads

    AB=AB(A0, B>0),\frac{\sqrt{A}}{\sqrt{B}}=\sqrt{\frac{A}{B}}\quad (A\ge 0,\ B>0),

    and it is far less work here than simplifying 48x12\sqrt{48x^{12}} and 2x\sqrt{2x} separately. The assumption x>0x>0 is what guarantees both radicands are non-negative and the denominator is non-zero.

  2. Divide inside the single radical. Handle the number and the powers separately:

    482=24,x12x1=x11  48x122x=24x11.\frac{48}{2}=24,\qquad \frac{x^{12}}{x^{1}}=x^{11}\ \Longrightarrow\ \sqrt{\frac{48x^{12}}{2x}}=\sqrt{24x^{11}}.

  3. Split off the largest perfect squares. For the coefficient, 24=4624=4\cdot 6 with 4=224=2^2. For the variable, the largest even power below 1111 is 1010, so x11=x10xx^{11}=x^{10}\cdot x with x10=(x5)2x^{10}=(x^5)^2:

    24x11=46x10x=4x106x.\sqrt{24x^{11}}=\sqrt{4\cdot 6\cdot x^{10}\cdot x}=\sqrt{4}\cdot\sqrt{x^{10}}\cdot\sqrt{6x}.

  4. Take the roots that come out. Because x>0x>0, no absolute-value bars are needed:

    2x56x=2x56x.2\cdot x^{5}\cdot\sqrt{6x}=2x^{5}\sqrt{6x}.

  5. Confirm the result is fully simplified and correct. Under the remaining radical, 6=236=2\cdot 3 is square-free and xx appears to the first power, so nothing more escapes. Numerically at x=2x=2: 484096/4=196608/2=221.7025\sqrt{48\cdot 4096}/\sqrt{4}=\sqrt{196608}/2=221.7025, and 2(32)12=64(3.4641)=221.70252(32)\sqrt{12}=64(3.4641)=221.7025. The two agree.

Answer

2x56x2x^{5}\sqrt{6x}

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