Question

find. x (2+5x)7=84​

Answer 1

${\boxed {\underline {\red{answer}}}}$

Let's solve your equation step-by-step.

x(2+5x)(7)=84

Step 1: Simplify both sides of the equation.

$35 {x}^{2} + 14x = 84$

Step 2: Subtract 84 from both sides.

$35 {x}^{2} + 14x -\blue{84} = 84 - \blue {84}$

$35 {x}^{2} + 14x - 84= 0$

$For \: this \: equation:  \blue{ a=35},  \green{b=14},  \red{ c=-84}$

$\blue{35} {x}^{2} + \green{ 14x} + \red{ - 84 }= 0$

Step 3: Use quadratic formula

$with \: \blue{ a=35},  \green{b=14},  \red{ c=-84}$

$x = \frac{ - \green{b}± \sqrt{ { \green{b}}^{2} - 4 \blue{a} \red{c} } }{2 \blue{a} }$

$x = \frac{ - \green{14}± \sqrt{ { \green{(14)}}^{2} - 4 (\blue{35}) (\red{ - 84} ) } }{2 (\blue{35}) }$

$x = \frac{ - 14± \sqrt{11956} }{70}$

$x = \frac{ - 1}{5} + \frac{1}{5} \sqrt{61} \: \: or \: \: x = - 1 + \frac{ - 1}{5} \sqrt{61}$

${ \boxed {\tt{answer}}}$

$\small\boxed{x = \frac{ - 1}{5} + \frac{1}{5} \sqrt{61} \: \: or \: \: x = - 1 + \frac{ - 1}{5} \sqrt{61} }$