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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 $y = mx + c$. (b) In how many diffe... 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

Find the Cartesian equation of this line in the form $y = mx + c$

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Answer

To find the Cartesian equation, we start from the parametric equations:

  1. Isolate tt from the first equation: t=x13t = \frac{x - 1}{3}

  2. Substitute this expression for tt into the second equation: 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 us: 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

To find the number of arrangements of the letters in 'CONDOBOLIN', we note that the word contains 11 letters.

In the word, we have:

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

The total arrangements can be calculated using the formula for permutations of multiset: rac{n!}{n_1! \cdot n_2! \cdots n_k!} where:

  • nn = total number of items (letters),
  • n1n_1, n2n_2, ..., nkn_k = counts of each indistinguishable item.

Thus, we have: Arrangements=11!2!\text{Arrangements} = \frac{11!}{2!}

Calculating, 11!=3991680011! = 39916800 2!=22! = 2

Therefore: Arrangements=399168002=19958400\text{Arrangements} = \frac{39916800}{2} = 19958400

So, there are 19,958,400 different arrangements.

Step 3

Find $a$ and $b$

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Answer

Using the factor theorem, since x+1x + 1 is a factor, we know: P(1)=(1)3+a(1)2+b(1)12=0P(-1) = (-1)^3 + a(-1)^2 + b(-1) - 12 = 0

This simplifies to: 1+ab12=0ab=13(1)-1 + a - b - 12 = 0\Rightarrow a - b = 13 \quad (1)

Now using the remainder theorem: P(2)=23+a(22)+b(2)12=18P(2) = 2^3 + a(2^2) + b(2) - 12 = -18

This gives: 8+4a+2b12=184a+2b4=184a+2b=142a+b=7(2)8 + 4a + 2b - 12 = -18\Rightarrow 4a + 2b - 4 = -18\Rightarrow 4a + 2b = -14\Rightarrow 2a + b = -7 \quad (2)

Now, we can solve equations (1) and (2): Substituting (1) into (2):

  • From (1): b=a13b = a - 13 [-15][= 4\rightarrow \text{substituted into equation (2)}]
  • Thus, 2a+(a13)=72a + (a - 13) = -7 3a13=73a - 13 = -7 3a=6a=23a = 6\Rightarrow a = 2 b=213=11b = 2 - 13 = -11

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

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