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Question

If A + B = A + C and AB = AC, then which of the following is true?

The correct answer is B = C

Algebraic Equations Explained: Determining B and C

This problem asks us to determine the relationship between variables B and C, given two algebraic equations:

  • Equation 1: \(A + B = A + C\)
  • Equation 2: \(AB = AC\)

We will analyze each equation separately to see what conclusions can be drawn about B and C.

Analyzing the First Equation: \(A + B = A + C\)

Let's start with the first given equation and simplify it to find the relationship between B and C.

Given: \[A + B = A + C\]

To simplify this equation, we can perform the same operation on both sides to maintain equality. The most straightforward step here is to subtract the variable A from both sides of the equation.

Subtract A from both sides: \[(A + B) - A = (A + C) - A\]

This simplifies to: \[B = C\]

From the first equation, we can directly conclude that B must be equal to C.

Solving the Second Equation: \(AB = AC\)

Now, let's examine the second equation provided:

Given: \[AB = AC\]

To solve this equation for B and C, we need to consider two possible cases for the variable A.

Case 1: When A is Not Equal to Zero (\(A \neq 0\))

If A is any non-zero number, we can divide both sides of the equation by A. Dividing by a non-zero number is a valid algebraic operation that maintains the equality.

Divide both sides by A: \[\frac{AB}{A} = \frac{AC}{A}\]

This simplifies to: \[B = C\]

So, if A is not zero, the second equation also leads to the conclusion that B is equal to C.

Case 2: When A is Equal to Zero (\(A = 0\))

We must consider the possibility that A could be zero. If A is zero, then division by A is undefined, so we cannot simply divide both sides by A.

Let's substitute \(A = 0\) into both original equations:

  • For the first equation: \(A + B = A + C\)

    Substitute \(A = 0\):

    \[0 + B = 0 + C\] \[B = C\]

    This still implies that B must be equal to C.

  • For the second equation: \(AB = AC\)

    Substitute \(A = 0\):

    \[0 \times B = 0 \times C\] \[0 = 0\]

    This statement \(0 = 0\) is always true, regardless of the values of B and C. However, since the first equation \(A+B=A+C\) (which also holds true when A=0) has already established that \(B=C\), this \(0=0\) result from the second equation does not contradict or change our finding. It simply means that if A is zero, the second equation provides no new information about B and C beyond what the first equation gives.

Conclusion on Variables B and C

From our analysis of both equations, we consistently arrive at the same conclusion:

  • The first equation \(A + B = A + C\) directly simplifies to \(B = C\).
  • The second equation \(AB = AC\) also simplifies to \(B = C\) when \(A \neq 0\).
  • When \(A = 0\), the first equation still yields \(B = C\), and the second equation becomes \(0 = 0\), which is consistent with \(B = C\).

Therefore, given both conditions \(A + B = A + C\) and \(AB = AC\), the only logical conclusion is that B is equal to C.

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Important Questions from Logic Gates and Boolean Algebra

  1. In Boolean algebra, the term sum of products means

  2. The value of \(\rm \overline{A+B}\) is :

  3. The Boolean function Y = AB + CD is to be realized using only two-input NAND gates. The minimum number of gates required are:

  4. The minimum number of 2-input NAND gates required to realize the logic function $Y = AB + \bar A \bar B$ is

  5. The number of distinct Boolean expressions of four variables is-

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