Algebra · real student question

Simplify (3^5 * 27^3 * 9^4) / (3 * 81^4), giving the answer as a power of 3 and as a whole number.

Question

Simplify

35273943814\frac{3^{5}\cdot 27^{3}\cdot 9^{4}}{3\cdot 81^{4}}

Step-by-step solution

  1. Put everything over a single base. The exponent laws only combine powers that share a base, and 2727, 99 and 8181 are all powers of 33:

    27=33,9=32,81=34.27=3^{3},\qquad 9=3^{2},\qquad 81=3^{4}.

  2. Rewrite each factor using the power-of-a-power rule. Multiply the exponents:

    273=(33)3=39,94=(32)4=38,814=(34)4=316.27^{3}=\left(3^{3}\right)^{3}=3^{9},\qquad 9^{4}=\left(3^{2}\right)^{4}=3^{8},\qquad 81^{4}=\left(3^{4}\right)^{4}=3^{16}.

  3. Collect the numerator and the denominator separately. Multiplying like bases adds exponents:

    numerator=353938=35+9+8=322,\text{numerator}=3^{5}\cdot 3^{9}\cdot 3^{8}=3^{5+9+8}=3^{22},

    denominator=31316=31+16=317.\text{denominator}=3^{1}\cdot 3^{16}=3^{1+16}=3^{17}.

    The lone 33 counts as 313^1 — forgetting that exponent is the usual slip here.

  4. Divide by subtracting exponents.

    322317=32217=35.\frac{3^{22}}{3^{17}}=3^{22-17}=3^{5}.

  5. Evaluate and verify. 35=2433^{5}=243. As a check, the raw integers are 3527394=243196836561=313810596093^5\cdot27^3\cdot9^4=243\cdot19683\cdot6561=31\,381\,059\,609 and 3814=343046721=1291401633\cdot81^4=3\cdot43\,046\,721=129\,140\,163; dividing gives exactly 243243.

Answer

322317=35=243\frac{3^{22}}{3^{17}}=3^{5}=243

Need to solve a different problem like this? Open the solver →