Q. \(x^2-5x-14=0\)
Answer
We solve the quadratic \(x^2-5x-14=0\) by factoring:
Find two numbers that multiply to \(-14\) and add to \(-5\): \(-7\) and \(2\).
\[
x^2-5x-14=(x-7)(x+2)=0
\]
So \(x-7=0\) or \(x+2=0\).
\[
x=7 \quad \text{or} \quad x=-2
\]
Final answers: \(x=7\) or \(x=-2\).
Detailed Explanation
We want to solve the quadratic equation
\[
x^{2}-5x-14=0
\]
Step 1: Factor the quadratic (if possible).
For a quadratic in the form \(ax^{2}+bx+c\), factoring works when we can write it as \((x-r)(x-s)=0\), where \(r\) and \(s\) satisfy:
\[
r+s = 5 \quad \text{and} \quad rs = -14
\]
We need two numbers whose product is \(-14\) and whose sum is \(5\).
Step 2: Find the two numbers.
The factor pairs of \(14\) are \(1\cdot 14\) and \(2\cdot 7\). To get a product of \(-14\), one number must be negative:
\[
(-1)\cdot 14 = -14 \quad \text{and} \quad (-2)\cdot 7 = -14
\]
Now check their sums:
\[
(-1)+14 = 13 \quad (\text{not } 5)
\]
\[
(-2)+7 = 5 \quad (\text{works})
\]
Step 3: Write the factored form.
Since \(r=-2\) and \(s=7\), we can factor the quadratic as:
\[
x^{2}-5x-14 = (x-7)(x+2)
\]
Step 4: Use the zero product property.
If \((x-7)(x+2)=0\), then either:
\[
x-7=0 \quad \text{or} \quad x+2=0
\]
Step 5: Solve each linear equation.
First equation:
\[
x-7=0
\]
Add \(7\) to both sides:
\[
x=7
\]
Second equation:
\[
x+2=0
\]
Subtract \(2\) from both sides:
\[
x=-2
\]
Final Answer:
\[
x=7 \quad \text{or} \quad x=-2
\]
Graph
Algebra FAQ
Solve \(x^2-5x-14=0\) by factoring.
Use the quadratic formula for \(x^2-5x-14=0\).
Check the solutions \(x=7\) and \(x=-2\).
What is the discriminant of \(x^2-5x-14=0\)?
How do I know the factoring method works here?
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