QUESTION IMAGE
Question
which comparison of the two equations is accurate?
equation a: \\(\sqrt{x^2 + 3x - 6} = -\sqrt{x + 2}\\)
equation b: \\(\sqrt3{x^2 + 3x - 6} = \sqrt3{x + 2}\\)
\\(\bigcirc\\) both equations have different solutions because the square root of a number is not the same as the cube root of a number
\\(\bigcirc\\) both equations result in different equations after eliminating the radicals, so they have the different solutions.
\\(\bigcirc\\) both equations have the same potential solutions, but equation a might have extraneous solutions.
\\(\bigcirc\\) both equations have the same potential solutions, but equation b might have extraneous solutions.
Step1: Analyze Equation A
Equation A is a square - root equation: $\sqrt{x^{2}+3x - 6}=-\sqrt{x + 2}$. The square root function $y = \sqrt{u}$ has a range of $y\geq0$. So, the left - hand side $\sqrt{x^{2}+3x - 6}\geq0$, and the right - hand side $-\sqrt{x + 2}\leq0$. For the equation to hold, both sides must be equal to 0 (since a non - negative number equals a non - positive number only when both are 0). Also, when we solve square - root equations, we often square both sides to eliminate the square roots. But squaring can introduce extraneous solutions. For example, if we have an equation $\sqrt{a}=b$, squaring both sides gives $a = b^{2}$, but if $b$ is negative, the original equation may not hold (because the square root of $a$ is non - negative).
Step2: Analyze Equation B
Equation B is a cube - root equation: $\sqrt[3]{x^{2}+3x - 6}=\sqrt[3]{x + 2}$. The cube - root function $y=\sqrt[3]{u}$ has a domain of all real numbers and a range of all real numbers. If we cube both sides of a cube - root equation $\sqrt[3]{a}=\sqrt[3]{b}$, we get $a = b$ directly, and cubing does not introduce extraneous solutions because the cube - root function is one - to - one (for every real number $y$, there is exactly one real number $x$ such that $y=\sqrt[3]{x}$).
Step3: Compare the two equations
To solve Equation A:
First, note the domain restrictions. For $\sqrt{x^{2}+3x - 6}$ to be defined, $x^{2}+3x - 6\geq0$. For $\sqrt{x + 2}$ to be defined, $x+2\geq0\Rightarrow x\geq - 2$. Also, since $\sqrt{x^{2}+3x - 6}\geq0$ and $-\sqrt{x + 2}\leq0$, we must have $\sqrt{x^{2}+3x - 6}=0$ and $-\sqrt{x + 2}=0$. From $-\sqrt{x + 2}=0$, we get $\sqrt{x + 2}=0\Rightarrow x=-2$. Substitute $x = - 2$ into $x^{2}+3x - 6$: $(-2)^{2}+3\times(-2)-6=4 - 6 - 6=-8<0$. So, the domain of Equation A is actually empty? Wait, no, maybe a better way: square both sides of Equation A: $x^{2}+3x - 6=x + 2$. Then $x^{2}+2x - 8 = 0$. Factoring, we get $(x + 4)(x - 2)=0$. So, $x=-4$ or $x = 2$. But we need to check the domain: for $x=-4$, $\sqrt{(-4)^{2}+3\times(-4)-6}=\sqrt{16-12 - 6}=\sqrt{-2}$, which is not a real number. For $x = 2$, $\sqrt{4 + 6 - 6}=\sqrt{4}=2$, and $-\sqrt{2 + 2}=-\sqrt{4}=-2$. Since $2
eq - 2$, both solutions are extraneous? Wait, maybe my initial thought about the range was wrong. The right - hand side is $-\sqrt{x + 2}$, and the left - hand side is $\sqrt{x^{2}+3x - 6}$. Let's consider squaring both sides: $x^{2}+3x - 6=x + 2\Rightarrow x^{2}+2x - 8 = 0\Rightarrow x=-4$ or $x = 2$. For $x=-4$: LHS: $\sqrt{16-12 - 6}=\sqrt{-2}$ (undefined in real numbers). For $x = 2$: LHS: $\sqrt{4 + 6 - 6}=\sqrt{4}=2$; RHS: $-\sqrt{2 + 2}=-2$. So, no solution? But the key point is that when solving square - root equations (Equation A), we may get extraneous solutions. For Equation B, when we cube both sides, we get $x^{2}+3x - 6=x + 2\Rightarrow x^{2}+2x - 8 = 0$, which is the same quadratic equation as when we squared both sides of Equation A. But for Equation B, since cube - root is a one - to - one function, the solutions of the cubic - root equation (after cubing) are the solutions of the original equation. However, for Equation A, the solutions of the squared equation may not be solutions of the original square - root equation (extraneous solutions). So, both equations, when we eliminate the radicals (square for A, cube for B), lead to the same quadratic equation $x^{2}+2x - 8 = 0$, so they have the same potential solutions. But Equation A (square - root equation) might have extraneous solutions.
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Both equations have the same potential solutions, but equation A might have extraneous solutions.