Solve the proportion. $$\frac { x } { 21 } = \frac { 2 } { x + 1 }$$
A) $\quad x _ { 1 } = - 7 , x _ { 2 } = - 6$
B) $\quad x _ { 1 } = - 7 , x _ { 2 } = 6$
C) $\quad x _ { 1 } = 7 , x _ { 2 } = 6$
D) $\quad x _ { 1 } = 7 , x _ { 2 } = - 6$
E) no solutions

Question

Quizplus · Accepted Answer

Cross-multiplying the given proportion $\frac{x}{21} = \frac{2}{x + 1}$ gives $x(x + 1) = 42$, which simplifies to $x^2 + x - 42 = 0$. Factoring this quadratic equation yields $(x + 7)(x - 6) = 0$, leading to the solutions $x_1 = -7$ and $x_2 = 6$.

Solve the Proportion x21=2x+1\frac { x } { 21 } = \frac { 2 } { x + 1 }21x​=x+12​

Solve the Proportion $\frac { x } { 21 } = \frac { 2 } { x + 1 }$