Q. Convert the equation \(x^2-4x+3=0\). Complete the square.
Answer
To complete the square, start with
\[
x^2-4x+3=0.
\]
Move the constant:
\[
x^2-4x=-3.
\]
Complete the square on the left. Halve \(-4\) to get \(-2\), square to get \(4\):
\[
x^2-4x+4=-3+4.
\]
So
\[
(x-2)^2=1.
\]
Take square roots:
\[
x-2=\pm 1.
\]
Thus
\[
x=2\pm 1,
\]
giving
\[
x=1 \quad \text{or} \quad x=3.
\]
Detailed Explanation
We want to solve the equation by completing the square:
First, start with the given quadratic:
\[
x^2 – 4x + 3 = 0
\]
Step 1: Move the constant term to the other side
We isolate the part with \(x\) so that we can complete the square easily.
\[
x^2 – 4x = -3
\]
Step 2: Complete the square for \(x^2 – 4x\)
Recall the rule: to complete the square, take half of the coefficient of \(x\), square it, and add and subtract it appropriately.
Here, the coefficient of \(x\) in \(x^2 – 4x\) is \(-4\).
Compute half of \(-4\):
\[
\frac{-4}{2} = -2
\]
Now square \(-2\):
\[
(-2)^2 = 4
\]
So we will add and subtract \(4\) inside the expression \(x^2 – 4x\).
Rewrite the left side by grouping:
\[
x^2 – 4x + 4 – 4 = -3
\]
Group the first three terms to form a perfect square trinomial:
\[
(x^2 – 4x + 4) – 4 = -3
\]
Recognize the perfect square:
\[
(x – 2)^2 – 4 = -3
\]
Step 3: Add \(4\) to both sides
We want the square term by itself.
\[
(x – 2)^2 = -3 + 4
\]
Compute the right side:
\[
(x – 2)^2 = 1
\]
Step 4: Take the square root of both sides
If \((x – 2)^2 = 1\), then \(x – 2\) can be \(1\) or \(-1\).
\[
x – 2 = 1
\]
and
\[
x – 2 = -1
\]
Step 5: Solve each linear equation
First case:
\[
x – 2 = 1
\]
\[
x = 3
\]
Second case:
\[
x – 2 = -1
\]
\[
x = 1
\]
Final Answer
The solutions are:
\[
x = 1 \quad \text{or} \quad x = 3
\]
Graph
Algebra FAQ
Complete the square for \\(x^2-4x+3=0\\). What form do you get?
Solve \\((x-2)^2-1=0\\) for \\(x\\).
Check solutions \\(x=1\\) and \\(x=3\\) in \\(x^2-4x+3=0\\).
What is the role of \\(\\left(\\frac{-b}{2a}\\right)^2\\) for this quadratic?
How do you rewrite \\(x^2-4x\\) as a perfect square?
Why does \\(+3\\) become \\(-1\\) after completing the square?
Math, Geometry, Trigonometry, etc.