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e. n^th term is: f. n^th term is: g. n^th term is: Make notes on how you solved the sequences.

Mathematics

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Here are the solutions for the remaining parts of question 1 and for question 2.

Part e· 3 steps

  1. Find the common difference.

    The terms are −3,6,15,24-3, 6, 15, 24.
    The difference between consecutive terms is 6−(−3)=96 - (-3) = 9, 15−6=915 - 6 = 9, 24−15=924 - 15 = 9.
    The common difference is 9.

  2. Determine the nthn^{th} term.

    Since the common difference is 9, the nthn^{th} term will be of the form 9n+c9n + c.
    For n=1n=1, the term is −3-3. So, 9(1)+c=−3  ⟹  9+c=−3  ⟹  c=−129(1) + c = -3 \implies 9 + c = -3 \implies c = -12.
    Thus, the nthn^{th} term is 9n−129n - 12.

  3. Calculate the 10th10^{th} term.

    Substitute n=10n=10 into the nthn^{th} term formula:
    T10=9(10)−12=90−12=78T_{10} = 9(10) - 12 = 90 - 12 = 78.

    The nthn^{th} term is: 9n - 12\boxed{\text{9n - 12}}
    The 10th10^{th} term is: 78\boxed{\text{78}}

Part f· 3 steps

  1. Find the common difference.

    The terms are 13,17,21,2513, 17, 21, 25.
    The difference between consecutive terms is 17−13=417 - 13 = 4, 21−17=421 - 17 = 4, 25−21=425 - 21 = 4.
    The common difference is 4.

  2. Determine the nthn^{th} term.

    Since the common difference is 4, the nthn^{th} term will be of the form 4n+c4n + c.
    For n=1n=1, the term is 13. So, 4(1)+c=13  ⟹  4+c=13  ⟹  c=94(1) + c = 13 \implies 4 + c = 13 \implies c = 9.
    Thus, the nthn^{th} term is 4n+94n + 9.

  3. Calculate the 10th10^{th} term.

    Substitute n=10n=10 into the nthn^{th} term formula:
    T10=4(10)+9=40+9=49T_{10} = 4(10) + 9 = 40 + 9 = 49.

    The nthn^{th} term is: 4n + 9\boxed{\text{4n + 9}}
    The 10th10^{th} term is: 49\boxed{\text{49}}

Part g· 11 steps

  1. Find the common difference.

    The terms are −6,10,26,42-6, 10, 26, 42.
    The difference between consecutive terms is 10−(−6)=1610 - (-6) = 16, 26−10=1626 - 10 = 16, 42−26=1642 - 26 = 16.
    The common difference is 16.

  2. Determine the nthn^{th} term.

    Since the common difference is 16, the nthn^{th} term will be of the form 16n+c16n + c.
    For n=1n=1, the term is −6-6. So, 16(1)+c=−6  ⟹  16+c=−6  ⟹  c=−2216(1) + c = -6 \implies 16 + c = -6 \implies c = -22.
    Thus, the nthn^{th} term is 16n−2216n - 22.

  3. Calculate the 10th10^{th} term.

    Substitute n=10n=10 into the nthn^{th} term formula:
    T10=16(10)−22=160−22=138T_{10} = 16(10) - 22 = 160 - 22 = 138.

    The nthn^{th} term is: 16n - 22\boxed{\text{16n - 22}}
    The 10th10^{th} term is: 138\boxed{\text{138}}

    Problem solving - First sequence
    The given terms are T3=13T_3 = 13, T6=40T_6 = 40, T9=85T_9 = 85, T12=148T_{12} = 148.

  4. Determine the type of sequence.

    Let the nthn^{th} term be Tn=an2+bn+cT_n = an^2 + bn + c.
    Using the given terms:
    For n=3n=3: 9a+3b+c=139a + 3b + c = 13 (Eq 1)
    For n=6n=6: 36a+6b+c=4036a + 6b + c = 40 (Eq 2)
    For n=9n=9: 81a+9b+c=8581a + 9b + c = 85 (Eq 3)

  5. Solve the system of equations.

    Subtract (Eq 1) from (Eq 2): 27a+3b=2727a + 3b = 27 (Eq 4)
    Subtract (Eq 2) from (Eq 3): 45a+3b=4545a + 3b = 45 (Eq 5)
    Subtract (Eq 4) from (Eq 5): 18a=18  ⟹  a=118a = 18 \implies a = 1.
    Substitute a=1a=1 into (Eq 4): 27(1)+3b=27  ⟹  3b=0  ⟹  b=027(1) + 3b = 27 \implies 3b = 0 \implies b = 0.
    Substitute a=1,b=0a=1, b=0 into (Eq 1): 9(1)+3(0)+c=13  ⟹  9+c=13  ⟹  c=49(1) + 3(0) + c = 13 \implies 9 + c = 13 \implies c = 4.

  6. Determine the nthn^{th} term.

    The nthn^{th} term is Tn=1n2+0n+4=n2+4T_n = 1n^2 + 0n + 4 = n^2 + 4.

  7. Calculate the 10th10^{th} term.

    Substitute n=10n=10 into the nthn^{th} term formula:
    T10=102+4=100+4=104T_{10} = 10^2 + 4 = 100 + 4 = 104.

    The nthn^{th} term is: \boxed{\text{n^2 + 4}}
    The 10th10^{th} term is: 104\boxed{\text{104}}

    Problem solving - Second sequence
    The given terms are T6=199T_6 = 199, T12=1711T_{12} = 1711, T18=5815T_{18} = 5815. We need to find T10T_{10}.

  8. Determine the type of sequence.

    Let the nthn^{th} term be Tn=an2+bn+cT_n = an^2 + bn + c.
    Using the given terms:
    For n=6n=6: 36a+6b+c=19936a + 6b + c = 199 (Eq 1)
    For n=12n=12: 144a+12b+c=1711144a + 12b + c = 1711 (Eq 2)
    For n=18n=18: 324a+18b+c=5815324a + 18b + c = 5815 (Eq 3)

  9. Solve the system of equations.

    Subtract (Eq 1) from (Eq 2): 108a+6b=1512108a + 6b = 1512 (Eq 4)
    Subtract (Eq 2) from (Eq 3): 180a+6b=4104180a + 6b = 4104 (Eq 5)
    Subtract (Eq 4) from (Eq 5): 72a=2592  ⟹  a=3672a = 2592 \implies a = 36.
    Substitute a=36a=36 into (Eq 4): 108(36)+6b=1512  ⟹  3888+6b=1512  ⟹  6b=−2376  ⟹  b=−396108(36) + 6b = 1512 \implies 3888 + 6b = 1512 \implies 6b = -2376 \implies b = -396.
    Substitute a=36,b=−396a=36, b=-396 into (Eq 1): 36(36)+6(−396)+c=199  ⟹  1296−2376+c=199  ⟹  −1080+c=199  ⟹  c=127936(36) + 6(-396) + c = 199 \implies 1296 - 2376 + c = 199 \implies -1080 + c = 199 \implies c = 1279.

  10. Determine the nthn^{th} term.

    The nthn^{th} term is Tn=36n2−396n+1279T_n = 36n^2 - 396n + 1279.

  11. Calculate the 10th10^{th} term.

    Substitute n=10n=10 into the nthn^{th} term formula:
    T10=36(102)−396(10)+1279T_{10} = 36(10^2) - 396(10) + 1279
    T10=36(100)−3960+1279T_{10} = 36(100) - 3960 + 1279
    T10=3600−3960+1279T_{10} = 3600 - 3960 + 1279
    T10=−360+1279=919T_{10} = -360 + 1279 = 919.

    The nthn^{th} term is: \boxed{\text{36n^2 - 396n + 1279}}
    The 10th10^{th} term is: 919\boxed{\text{919}}

    2. Make notes on how you solved the sequences.
    For arithmetic sequences (like parts a-g), I found the common difference (dd) between consecutive terms. The nthn^{th} term was then determined using the formula Tn=a+(n−1)dT_n = a + (n-1)d, where aa is the first term.
    For quadratic sequences (like the "Problem solving" sections), I used the general form Tn=an2+bn+cT_n = an^2 + bn + c. By substituting the given term positions (nn) and their values (TnT_n), I created a system of simultaneous equations to solve for the coefficients a,b,a, b, and cc.

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