Subjects algebra

Factor And Solve

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Factor And Solve


1. The problem gives four quadratic equations and partly factored forms with one missing factor in each. We will complete the factoring and then find the two values of $x$ for each. 2. For $x^2 + 6x + 8 = 0$, the given factor is $(x + 2)$. To find the missing factor, divide the quadratic by $(x + 2)$ or find the other root: The roots multiply to $8$ and add to $6$. Since $2$ is a root (from $x+2=0$), the other root is $4$ because $2 \times 4 = 8$ and $2 + 4 = 6$. So, missing factor is $(x + 4)$. Solutions: $$x = -2 \text{ or } x = -4$$ 3. For $x^2 - 4x + 3 = 0$ with factor $(x - 3)$ given, the roots must multiply to $3$ and sum to $4$ (since coefficient of $x$ is $-4$ and factoring signs show roots are positive). One root is $3$, so the other root is $1$. Missing factor: $$(x - 1)$$ Solutions: $$x = 3 \text{ or } x = 1$$ 4. For $x^2 + 4x - 21 = 0$, given factor is $(x - 3)$. Roots multiply to $-21$ and add to $4$. Since $3$ is a root, the other root $r$ satisfies $3 \times r = -21$, so $r = -7$. Missing factor: $$(x + 7)$$ Solutions: $$x = 3 \text{ or } x = -7$$ 5. For $x^2 - 8x - 9 = 0$, given factor is $(x + 1)$. Roots multiply to $-9$ and add to $8$ (opposite sign from middle term). Since root $-1$ from $(x + 1)$ is known, the other root $r$ satisfies $(-1) \times r = -9$, so $r = 9$. Missing factor: $$(x - 9)$$ Solutions: $$x = -1 \text{ or } x = 9$$