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Solve the given problems. If \((x+k)(x-1)=x^{2}+k(x+2)-(x-3),\) find the value of \(k\).

Short Answer

Expert verified
The value of \(k\) is \(-1\).

Step by step solution

01

Simplify the Right Side

First, simplify the expression on the right side of the equation \(x^{2}+k(x+2)-(x-3)\). Distribute the \(k\) into \(x+2\) to get \(kx + 2k\). Also, distribute the negative sign into \(x-3\) to get \(-x + 3\). So the expression simplifies to \(x^2 + kx + 2k - x + 3\).
02

Combine Like Terms on the Right Side

Now, combine like terms in the expression \(x^2 + kx + 2k - x + 3\). Combine the \(kx\) and \(-x\) terms to get \((k-1)x\). So the simplified expression is \(x^2 + (k-1)x + 2k + 3\).
03

Expand the Left Side

Expand the left side of the equation \((x + k)(x - 1)\) using the distributive property: \((x + k)(x - 1) = x(x - 1) + k(x - 1)\). This gives \(x^2 - x + kx - k\), which simplifies to \(x^2 + (k-1)x - k\).
04

Equate the Left and Right Sides

Since both expressions are equal, equate the coefficients from both sides: \(x^2 + (k-1)x - k = x^2 + (k-1)x + 2k + 3\).
05

Solve for \(k\)

From \(-(k) = 2k + 3\), solve for \(k\). Add \(k\) to both sides: \(-k + k = 2k + 3 + k\) simplifies to \(0 = 3k + 3\). Then, subtract 3 from both sides: \(-3 = 3k\). Divide by 3: \(-1 = k\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Polynomial equations
A polynomial equation involves a sum of terms, each consisting of a variable raised to a non-negative integer power, multiplied by a coefficient. Solving polynomial equations, like the one given in the exercise, often requires simplifying and manipulating the equation until you can solve for unknown variables such as the coefficient \( k \) in this case.

Here, we first need to simplify both sides of the equation \((x+k)(x-1) = x^{2}+k(x+2)-(x-3)\). Notice how each part on the right is a polynomial expression, which encapsulates the essence of polynomial equations.
  • The equation is balanced on both sides, meaning whatever we do (like add, multiply, or factor), must be applied to both sides consistently.
  • Identifying like terms and combining them is crucial to ensure a smooth process of solving for \( k \).
By maintaining the balance and simplifying strategically, we aim for a point where we can make meaningful comparisons between coefficients, easing the solving process.
Simplifying expressions
Simplification is a core tool in algebra, and here it plays a pivotal role. In solving our exercise, simplifying ensures each side of the equation is in its simplest form for easy manipulation and comparison.

Starting with the right side \((x^{2}+k(x+2)-(x-3))\), we see this as a sum of several grouped terms. The goal is to make these terms as straightforward as possible:
  • Distribute constants and variables correctly, which often involves applying the distributive property.
  • Combine like terms, such as adding \( kx \) and \( -x \) to get \((k-1)x\).
Excelling at simplification ensures you can easily view where variables and coefficients relate to each other, setting a clear pathway for solving an equation like this one. In our task, efficient simplification enabled us to reveal \( k \).
Distributive property
The distributive property is a fundamental tool in algebra used in both expansion and simplification. It is expressed as \( a(b+c) = ab + ac \). This allows you to multiply a single term across terms within parentheses, making it easier to work with expressions in standard polynomial form.

In our exercise, employing the distributive property, we had:\(k(x+2)\), which distributes to \(kx + 2k\). Similarly, the expression \((x+k)(x-1)\) is expanded using the property to become \(x^2 - x + kx - k\).
  • This property is instrumental in breaking down complex terms into simpler, manageable units.
  • It ensures each component of an equation is correctly accounted for and helps reveal hidden relationships between terms.
By ensuring proper use of this property, solving the equation for \( k \) becomes straightforward and logical, illuminating the algebraic structure buried within polynomial equations.

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