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Question

The three roots of the equation f(x) = 0 are x = {-2, 0, 3}. What are the three values of x for which f (x - 3) = 0?

The correct answer is

1, 3, 6

Understanding Function Transformation and Roots

The question asks us to find the new roots of a transformed function, specifically $f(x - 3) = 0$, given the roots of the original function $f(x) = 0$. The original roots are provided as $x = \{-2, 0, 3\}$.

What is a Root?

A root of an equation $f(x) = 0$ is a value of $x$ that makes the equation true, meaning $f(x)$ evaluates to zero. For the given equation $f(x) = 0$, the roots are the specific $x$-values where the function's graph intersects the x-axis.

Understanding the Transformation $f(x - 3)$

The transformation from $f(x)$ to $f(x - 3)$ represents a horizontal shift of the function's graph. Specifically, replacing $x$ with $(x - 3)$ shifts the entire graph 3 units to the right.

Think about it this way: If $f(a) = 0$ (meaning 'a' is a root of $f(x)$), then for $f(x - 3)$ to be zero, the input to the function, which is $(x - 3)$, must be equal to 'a'. So, we set the new input $(x - 3)$ equal to the old roots.

Calculating the New Roots

We need to find the values of $x$ for which $f(x - 3) = 0$. This means the expression $(x - 3)$ must take on the values of the original roots.

  • Original root 1: $x = -2$
  • Original root 2: $x = 0$
  • Original root 3: $x = 3$

We set the argument of the new function, $(x - 3)$, equal to each of the original roots:

  1. Step 1: Set $x - 3$ equal to the first original root (-2).

    $$x - 3 = -2$$

    Add 3 to both sides to solve for $x$:

    $$x = -2 + 3$$

    $$x = 1$$

  2. Step 2: Set $x - 3$ equal to the second original root (0).

    $$x - 3 = 0$$

    Add 3 to both sides to solve for $x$:

    $$x = 0 + 3$$

    $$x = 3$$

  3. Step 3: Set $x - 3$ equal to the third original root (3).

    $$x - 3 = 3$$

    Add 3 to both sides to solve for $x$:

    $$x = 3 + 3$$

    $$x = 6$$

Conclusion

By applying the horizontal shift transformation, we find that the new values of $x$ for which $f(x - 3) = 0$ are $1$, $3$, and $6$. This corresponds to shifting the original roots $\{-2, 0, 3\}$ three units to the right on the number line.

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Important Questions from Numerical Computation

  1. A cube of side 3 units is formed using a set of smaller cubes of side 1 unit. Find the proportion of the number of faces of the smaller cubes visible to those which are NOT visible.

  2. What is the average of all multiples of 10 from 2 to 198?

  3. Ratio of the angles of a triangle are 1 : 2 : 6. What is the smallest angle?

  4. A deposit in a bank, which pays interest on its deposits compounded daily, grows to Rs. 80,000 for 500 days and to 88,000 for 1000 days. What would be its value (in Rs.) for 1500 days?

  5. Among A, B, C and D, there is a lawyer, a doctor, a teacher and a journalist. They drink exactly one each of tea, coffee, lemonade and milk. If neither the lawyer nor the teacher drinks milk, B drinks coffee, A is the teacher and C is the doctor and drinks tea, then which of the following is FALSE?

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