2a) Rationalize the following surds then solve.

Mathematics

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Okay Benoni, let's tackle these surds and integrals.

2a) Rationalize the following surds then solve.

i) 53\frac{5}{\sqrt{3}}

  1. Multiply the numerator and denominator by 3\sqrt{3} to rationalize.

    53×33=533\frac{5}{\sqrt{3}} \times \frac{\sqrt{3}}{\sqrt{3}} = \frac{5\sqrt{3}}{3}

    The rationalized expression is 533\boxed{\frac{5\sqrt{3}}{3}}.

    ii) 33\frac{3}{\sqrt{3}}

  2. Multiply the numerator and denominator by 3\sqrt{3}.

    33×33=333\frac{3}{\sqrt{3}} \times \frac{\sqrt{3}}{\sqrt{3}} = \frac{3\sqrt{3}}{3}
  3. Simplify the expression.

    333=3\frac{3\sqrt{3}}{3} = \sqrt{3}

    The rationalized expression is 3\boxed{\sqrt{3}}.

    iii) 42\frac{4}{\sqrt{2}}

  4. Multiply the numerator and denominator by 2\sqrt{2}.

    42×22=422\frac{4}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}} = \frac{4\sqrt{2}}{2}
  5. Simplify the expression.

    422=22\frac{4\sqrt{2}}{2} = 2\sqrt{2}

    The rationalized expression is 22\boxed{2\sqrt{2}}.

    iv) 12−5\frac{1}{\sqrt{2}-\sqrt{5}}

  6. Multiply the numerator and denominator by the conjugate of the denominator, which is 2+5\sqrt{2}+\sqrt{5}.

    12−5×2+52+5\frac{1}{\sqrt{2}-\sqrt{5}} \times \frac{\sqrt{2}+\sqrt{5}}{\sqrt{2}+\sqrt{5}}
  7. Expand the numerator and denominator.

    Remember (a−b)(a+b)=a2−b2(a-b)(a+b) = a^2-b^2.

    2+5(2)2−(5)2=2+52−5\frac{\sqrt{2}+\sqrt{5}}{(\sqrt{2})^2 - (\sqrt{5})^2} = \frac{\sqrt{2}+\sqrt{5}}{2 - 5} 2+5−3=−2+53\frac{\sqrt{2}+\sqrt{5}}{-3} = -\frac{\sqrt{2}+\sqrt{5}}{3}

    The rationalized expression is −2+53\boxed{-\frac{\sqrt{2}+\sqrt{5}}{3}}.

    2b) Simplify the following Surds.

    i) 32+98\sqrt{32} + 9\sqrt{8}

  8. Simplify each surd by finding perfect square factors.

    32=16×2=42\sqrt{32} = \sqrt{16 \times 2} = 4\sqrt{2} 8=4×2=22\sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2}
  9. Substitute the simplified surds back into the expression and combine like terms.

    42+9(22)=42+1824\sqrt{2} + 9(2\sqrt{2}) = 4\sqrt{2} + 18\sqrt{2} 42+182=2224\sqrt{2} + 18\sqrt{2} = \boxed{22\sqrt{2}}

    ii) 220+125−352\sqrt{20} + \sqrt{125} - 3\sqrt{5}

  10. Simplify each surd.

    20=4×5=25\sqrt{20} = \sqrt{4 \times 5} = 2\sqrt{5} 125=25×5=55\sqrt{125} = \sqrt{25 \times 5} = 5\sqrt{5}
  11. Substitute the simplified surds and combine like terms.

    2(25)+55−352(2\sqrt{5}) + 5\sqrt{5} - 3\sqrt{5} 45+55−354\sqrt{5} + 5\sqrt{5} - 3\sqrt{5} (4+5−3)5=65(4+5-3)\sqrt{5} = 6\sqrt{5}

    The simplified expression is 65\boxed{6\sqrt{5}}.

    iii) 98−32−22\sqrt{98} - \sqrt{32} - 2\sqrt{2}

  12. Simplify each surd.

    98=49×2=72\sqrt{98} = \sqrt{49 \times 2} = 7\sqrt{2} 32=16×2=42\sqrt{32} = \sqrt{16 \times 2} = 4\sqrt{2}
  13. Substitute the simplified surds and combine like terms.

    72−42−227\sqrt{2} - 4\sqrt{2} - 2\sqrt{2} (7−4−2)2=12=2(7-4-2)\sqrt{2} = 1\sqrt{2} = \sqrt{2}

    The simplified expression is 2\boxed{\sqrt{2}}.

    2c) Integrate all with respect to x the following simple equation.

    i) 8x28x^2

  14. Apply the power rule for integration, ∫xndx=xn+1n+1+C\int x^n dx = \frac{x^{n+1}}{n+1} + C.

    ∫8x2 dx=8x2+12+1+C\int 8x^2 \,dx = 8 \frac{x^{2+1}}{2+1} + C =8x33+C= 8 \frac{x^3}{3} + C

    The integral is 83x3+C\boxed{\frac{8}{3}x^3 + C}.

    ii) ∫dx3x+2\int \frac{dx}{3x+2}

  15. Use the integration rule ∫1ax+bdx=1aln⁡∣ax+b∣+C\int \frac{1}{ax+b} dx = \frac{1}{a} \ln|ax+b| + C.

    Here a=3a=3 and b=2b=2.

    ∫13x+2 dx=13ln⁡∣3x+2∣+C\int \frac{1}{3x+2} \,dx = \frac{1}{3} \ln|3x+2| + C

    The integral is 13ln⁡∣3x+2∣+C\boxed{\frac{1}{3}\ln|3x+2| + C}.

    iii) x4+x+4x3\frac{x^4+x+4}{x^3}

  16. Rewrite the expression by dividing each term in the numerator by x3x^3.

    x4x3+xx3+4x3=x+x−2+4x−3\frac{x^4}{x^3} + \frac{x}{x^3} + \frac{4}{x^3} = x + x^{-2} + 4x^{-3}
  17. Integrate each term using the power rule.

    ∫(x+x−2+4x−3) dx=∫x dx+∫x−2 dx+∫4x−3 dx\int (x + x^{-2} + 4x^{-3}) \,dx = \int x\,dx + \int x^{-2}\,dx + \int 4x^{-3}\,dx =x1+11+1+x−2+1−2+1+4x−3+1−3+1+C= \frac{x^{1+1}}{1+1} + \frac{x^{-2+1}}{-2+1} + 4\frac{x^{-3+1}}{-3+1} + C =x22+x−1−1+4x−2−2+C= \frac{x^2}{2} + \frac{x^{-1}}{-1} + 4\frac{x^{-2}}{-2} + C =x22−1x−42x2+C= \frac{x^2}{2} - \frac{1}{x} - \frac{4}{2x^2} + C =x22−1x−2x2+C= \frac{x^2}{2} - \frac{1}{x} - \frac{2}{x^2} + C

    The integral is x22−1x−2x2+C\boxed{\frac{x^2}{2} - \frac{1}{x} - \frac{2}{x^2} + C}.

    2d) Write down The Conjugate of the Surds.

    i) 3+2\sqrt{3}+\sqrt{2}

    The conjugate of 3+2\sqrt{3}+\sqrt{2} is 3−2\boxed{\sqrt{3}-\sqrt{2}}.

    ii) 13+527\frac{13+5\sqrt{2}}{7}

    The conjugate of the surd part 13+5213+5\sqrt{2} is 13−52\boxed{13-5\sqrt{2}}. (The denominator does not change for the conjugate of the expression itself, only the sign of the surd term in the numerator).

    iii) 1−2+51-2+\sqrt{5}

  18. Simplify the expression first.

    1−2+5=−1+51-2+\sqrt{5} = -1+\sqrt{5}
  19. Write down the conjugate.

    The conjugate of −1+5-1+\sqrt{5} is −1−5\boxed{-1-\sqrt{5}}.

    iv) 57+53+7−35\sqrt{7}+5\sqrt{3}+\sqrt{7}-\sqrt{3}

  20. Simplify the expression by combining like terms.

    (57+7)+(53−3)=67+43(5\sqrt{7}+\sqrt{7}) + (5\sqrt{3}-\sqrt{3}) = 6\sqrt{7} + 4\sqrt{3}
  21. Write down the conjugate.

    The conjugate of 67+436\sqrt{7}+4\sqrt{3} is 67−43\boxed{6\sqrt{7}-4\sqrt{3}}.

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