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The parametric equations of a line are given below - HSC - SSCE Mathematics Extension 1 - Question 11 - 2023 - Paper 1

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The parametric equations of a line are given below. $x = 1 + 3t$ $y = 4t$ Find the Cartesian equation of this line in the form $y = mx + c$. In how many dif... show full transcript

Worked Solution & Example Answer:The parametric equations of a line are given below - HSC - SSCE Mathematics Extension 1 - Question 11 - 2023 - Paper 1

Step 1

The parametric equations of a line are given below. Find the Cartesian equation of this line in the form y = mx + c.

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Answer

To eliminate the parameter tt, we can express tt in terms of xx using the first equation:

  1. From x=1+3tx = 1 + 3t, we have: t=x13t = \frac{x - 1}{3}

  2. Now, substitute tt in the second equation for yy: y=4t=4(x13)=4(x1)3=4x43y = 4t = 4 \left( \frac{x - 1}{3} \right) = \frac{4(x - 1)}{3} = \frac{4x - 4}{3}

  3. Rearranging gives: y=43x43y = \frac{4}{3}x - \frac{4}{3}

Thus, the Cartesian equation is y=43x43y = \frac{4}{3}x - \frac{4}{3}.

Step 2

In how many different ways can all the letters of the word CONDOBOLIN be arranged in a line?

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Answer

The word CONDOBOLIN has 12 letters in total with some repetitions:

  • C: 1
  • O: 2
  • N: 2
  • D: 1
  • B: 1
  • L: 1
  • I: 1

Using the formula for permutations of multiset: extTotalarrangements=n!n1!n2!nk! ext{Total arrangements} = \frac{n!}{n_1! \cdot n_2! \cdots n_k!}

Substituting the values: extTotalarrangements=12!2!2!1!1!1!1!1! ext{Total arrangements} = \frac{12!}{2! \cdot 2! \cdot 1! \cdot 1! \cdot 1! \cdot 1! \cdot 1!}

Calculating gives: =4790016004=119750400= \frac{479001600}{4} = 119750400

Therefore, the total number of arrangements is 119750400.

Step 3

Consider the polynomial P(x) = x^3 + ax^2 + bx - 12, where a and b are real numbers. Find a and b.

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Answer

Using the factor theorem, since x+1x + 1 is a factor:

  1. Evaluate P(1)P(-1): P(1)=(1)3+a(1)2+b(1)12=1+ab12=0P(-1) = (-1)^3 + a(-1)^2 + b(-1) - 12 = -1 + a - b - 12 = 0 a - b - 13 = 0 \\ \Rightarrow a - b = 13 \tag{1}

Using the remainder theorem, since the remainder when divided by x2x - 2 is -18: 2. Evaluate P(2)P(2): P(2)=(2)3+a(2)2+b(2)12=8+4a+2b12=18P(2) = (2)^3 + a(2)^2 + b(2) - 12 = 8 + 4a + 2b - 12 = -18 Simplifying gives: 4a + 2b - 4 = -18 \\ \Rightarrow 4a + 2b = -14 \\ \Rightarrow 2a + b = -7 \tag{2}

Now, solve equations (1) and (2) together:

  • From (1): ( b = a - 13 \ ext{Substituting into (2):}) 3a - 13 = -7 \\ \Rightarrow 3a = 6 \\ \Rightarrow a = 2$$
  • Substitute back to find bb: b=213=11b = 2 - 13 = -11

Thus, a=2a = 2 and b=11b = -11.

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