Maths Olympiad Prep

Track / Stage 3 / 22 of 260 #22 of 1964

Problem 22

AMC 10/12, early questions
Algebra Difficulty 3.0 Find the answer

If the value of the fraction x24x+2\frac{{x}^{2}-4}{x+2} is 00, then x=x=____.

A number or a short expression. Spacing, $ signs and \frac vs / are all fine.

Official solution

To solve the equation x24x+2=0\frac{{x}^{2}-4}{x+2}=0, we start by setting the numerator equal to zero, as the value of a fraction is zero if and only if its numerator is zero. Thus, we have:

x24=0x^{2}-4=0

This can be factored into:

(x2)(x+2)=0(x-2)(x+2)=0

From this, we find two possible values for xx:

1. x2=0x=2x-2=0 \Rightarrow x=2
2. x+2=0x=2x+2=0 \Rightarrow x=-2

However, we must also consider the denominator of the original fraction, x+2x+2, to ensure it is not zero, as division by zero is undefined.

- When x=2x=2, the denominator x+2=4x+2=4, which is not equal to zero. Therefore, x=2x=2 is a valid solution.
- When x=2x=-2, the denominator x+2=0x+2=0, which would make the fraction undefined. Therefore, x=2x=-2 is not a valid solution.

Thus, the only value of xx for which the fraction x24x+2\frac{{x}^{2}-4}{x+2} is 00 is x=2x=2.

x=2\boxed{x=2}

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.