Chapter 3: Problem 59
Solve. $$\sqrt{x+7}=x+1$$
Short Answer
Expert verified
The solution is \ x = 2 \
Step by step solution
01
- Isolate the Radical Expression
The radical expression \(\root{x+7}\) is already isolated on one side of the equation: \[ \root{x+7} = x+1 \].
02
- Square Both Sides
Square both sides of the equation to eliminate the radical: \[ (\root{x+7})^2 = (x+1)^2 \] This simplifies to: \[ x+7 = (x+1)(x+1) \] Expand the right side: \[ x+7 = x^2 + 2x + 1 \]}, {
03
- Rearrange into a Standard Quadratic Equation
Move all terms to one side of the equation to set the quadratic expression to zero: \[ x+7 - (x^2 + 2x + 1) = 0 \] Combine like terms: \[ -x^2 - x + 6 = 0 \] Multiply the entire equation by -1 to simplify: \[ x^2 + x - 6 = 0 \]
04
- Factor the Quadratic Equation
Factor the quadratic equation \ x^2 + x - 6 \ : \[ (x + 3)(x - 2) = 0 \]
05
- Find the Solutions
Set each factor equal to zero and solve for x: \[ x + 3 = 0 \] \[ x = -3 \] \[ x - 2 = 0 \] \[ x = 2 \]
06
- Verify the Solutions
Substitute both solutions back into the original equation \ \root{x+7} = x + 1 \ to verify: \[ x = -3 \] \[ \root{-3 + 7} = -3 + 1 \] \[ \root{4} = -2 \] which is false. Therefore, \ x = -3 \ is not a solution. Verifying \ x = 2 \ : \[ \root{2 + 7} = 2 + 1 \] \[ \root{9} = 3 \] which is true. Therefore, \ x = 2 \ is a solution.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equations
Quadratic equations are a type of polynomial equation that follow the standard form: \[ ax^2 + bx + c = 0 \]Here,
In the given exercise, after squaring both sides, we obtain a quadratic equation from \[ x + 7 = x^2 + 2x + 1.\]Rearranging the terms, we get \[ -x^2 - x + 6 = 0. \] Multiplying the entire equation by -1 simplifies it to the standard quadratic form \[ x^2 + x - 6 = 0. \]
- a, b,
- and c are constants,
- and x represents the variable.
In the given exercise, after squaring both sides, we obtain a quadratic equation from \[ x + 7 = x^2 + 2x + 1.\]Rearranging the terms, we get \[ -x^2 - x + 6 = 0. \] Multiplying the entire equation by -1 simplifies it to the standard quadratic form \[ x^2 + x - 6 = 0. \]
Factoring
Factoring is a method used to solve quadratic equations by expressing the quadratic as a product of its binomial factors. Consider \[ x^2 + x - 6 = 0.\]We look for two numbers that multiply to -6 (the constant term) and add up to 1 (the coefficient of x).
These numbers are +3 and -2 because
Setting each factor equal to zero gives the solutions:\[ x + 3 = 0 \rightarrow x = -3, \]\[ x - 2 = 0 \rightarrow x = 2. \]
These numbers are +3 and -2 because
- 3 * -2 = -6,
- 3 + (-2) = 1.
Setting each factor equal to zero gives the solutions:\[ x + 3 = 0 \rightarrow x = -3, \]\[ x - 2 = 0 \rightarrow x = 2. \]
Verification of Solutions
Verifying solutions ensures the values found actually satisfy the original equation. Even if algebraic manipulation says a value is a solution, it must still work in the context of the original problem.
Here, we substitute the solutions back into the original radical equation \[ \root{x+7} = x + 1. \]
Here, we substitute the solutions back into the original radical equation \[ \root{x+7} = x + 1. \]
- For x = -3:
- For x = 2:
\[ \root{-3 + 7} = -3 + 1 \ \rightarrow \root{4} eq -2 \]
which is false. Therefore, x = -3 is not a solution.
\[ \root{2 + 7} = 2 + 1 \ \rightarrow \root{9} = 3 \ \rightarrow \text{which is true}. \]