- Identify coefficients \(a=4, b=-17, c=4\) in the trinomial \(4x^2 - 17x + 4\).
- Use the AC method to find two numbers that multiply to \(ac = 16\) and add to \(b = -17\), which are \(-16\) and \(-1\).
- Rewrite the trinomial as \(4x^2 - 16x - x + 4\) and factor by grouping to get \(4x(x - 4) - 1(x - 4)\).
- Conclude that the final factored form is \(\boxed{(4x - 1)(x - 4)}\).
Explanation
- Analyzing the Trinomial
To factor the quadratic trinomial \(4x^2 - 17x + 4\), we begin by identifying the coefficients. The trinomial is of the standard form \(ax^2 + bx + c\), where \(a = 4\), \(b = -17\), and \(c = 4\). Our goal is to express this trinomial as the product of two linear binomials of the form \((dx + e)(fx + g)\).
- Finding the Factors of the AC Product
We use the AC method to factor the trinomial. First, we find the product of the leading coefficient \(a\) and the constant term \(c\), which is \(a \times c = 4 \times 4 = 16\). Next, we search for two numbers that multiply to \(16\) and add up to the middle coefficient \(b = -17\). Since the product is positive and the sum is negative, both numbers must be negative. Testing the factors of 16, we find that \(-1\) and \(-16\) satisfy both conditions: \((-1) \times (-16) = 16\) and \((-1) + (-16) = -17\).
- Factoring by Grouping
Now, we rewrite the middle term \(-17x\) using the two numbers found: \(-16x\) and \(-1x\). The expression becomes:
\[4x^2 - 16x - 1x + 4\]
Next, we perform factoring by grouping. We group the first two terms and the last two terms:
\[(4x^2 - 16x) - (x - 4)\]
From the first group, we can factor out \(4x\):
\[4x(x - 4) - 1(x - 4)\]
Now, we see a common binomial factor \((x - 4)\). Factoring it out, we obtain:
\[(4x - 1)(x - 4)\]
- Conclusion and Verification
We have successfully factored the trinomial \(4x^2 - 17x + 4\) into \((4x - 1)(x - 4)\). We can verify this by expanding the product:
\[(4x - 1)(x - 4) = 4x^2 - 16x - 1x + 4 = 4x^2 - 17x + 4\]
The expansion confirms our result. Thus, the factored form of the trinomial is \(\boxed{(4x - 1)(x - 4)}\).
Examples
Factoring quadratic expressions is a fundamental skill used in physics and engineering to solve problems involving motion. For example, if you are modeling the trajectory of a ball thrown into the air, its height \(h\) at time \(t\) might be given by a quadratic equation like \(h(t) = -4t^2 + 17t + 4\). Factoring the expression allows you to easily find the "roots" of the equation, which represent the times when the ball hits the ground (\(h=0\)). Mastering this process helps you solve for these critical points efficiently and understand the physical behavior of the object.