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Question 1: Given the function $f(x) = 3x^2 + 2x - 5$, determine: (a) The vertex of the parabola - HSC - SSCE Chemistry - Question 11 - 2017 - Paper 1

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Question-1:--Given-the-function-$f(x)-=-3x^2-+-2x---5$,-determine:--(a)-The-vertex-of-the-parabola-HSC-SSCE Chemistry-Question 11-2017-Paper 1.png

Question 1: Given the function $f(x) = 3x^2 + 2x - 5$, determine: (a) The vertex of the parabola. (b) The axis of symmetry of the parabola. (c) The y-intercept o... show full transcript

Worked Solution & Example Answer:Question 1: Given the function $f(x) = 3x^2 + 2x - 5$, determine: (a) The vertex of the parabola - HSC - SSCE Chemistry - Question 11 - 2017 - Paper 1

Step 1

(a) The vertex of the parabola.

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Answer

To find the vertex of the parabola defined by the function f(x)=ax2+bx+cf(x) = ax^2 + bx + c, we use the formula for the x-coordinate of the vertex, given by:

xv=b2ax_v = -\frac{b}{2a}

For our function, a=3a = 3 and b=2b = 2. Thus:

xv=223=13x_v = -\frac{2}{2 \cdot 3} = -\frac{1}{3}

Now substitute xvx_v back into the original function to find the y-coordinate:

f(13)=3(13)2+2(13)5=319235=13235=523f(-\frac{1}{3}) = 3(-\frac{1}{3})^2 + 2(-\frac{1}{3}) - 5 = 3\cdot\frac{1}{9} - \frac{2}{3} - 5 = \frac{1}{3} - \frac{2}{3} - 5 = -5\frac{2}{3}

Thus, the vertex is at (13,523)(-\frac{1}{3}, -5\frac{2}{3}).

Step 2

(b) The axis of symmetry of the parabola.

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Answer

The axis of symmetry can be determined using the x-coordinate of the vertex, found in part (a). Therefore, the axis of symmetry is the vertical line:

x=13.x = -\frac{1}{3}.

Step 3

(c) The y-intercept of the function.

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Answer

To find the y-intercept, we evaluate the function at x=0x = 0:

f(0)=3(0)2+2(0)5=5.f(0) = 3(0)^2 + 2(0) - 5 = -5.

Thus, the y-intercept is at the point (0,5)(0, -5).

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