Question

Ache a raiz da equação: X elevado a 2-x-20=0

Answer 1

$\mathbf {x^2 - x - 20 = 0}$

$\mathbf {a = 1, \ b = -1 , \ c = -20}$

$\mathbf {\Delta = b^2 - 4 \times a \times c}$

$\mathbf {\Delta = (-1)^2 - 4 \times 1 \times (-20)}$

$\mathbf {\Delta = 1 - (-80)}$

$\mathbf {\Delta = 1 + 80}$

$\mathbf {\Delta = 81}$

$\mathbf {x = \frac { -b \ \pm \ \sqrt{\Delta} } { 2 \times a } }$

$\mathbf {x = \frac { - ( - 1) \ \pm \ \sqrt{81}} { 2 \times 1 } }$

$\mathbf {x = \frac{ 1 \ \pm \ 9} { 2 } }$

$\mathbf {x_1 = \frac { 1 \ + \ 9 } { 2 } }$

$\mathbf {x_1 = \frac { 10 } { 2 } }$

$\green {\mathbf {\boxed { x_1 = 5} } }$

$\mathbf {x_2 = \frac { 1 \ - \ 9 }{ 2 } }$

$\mathbf {x_2 = \frac { -8 } { 2 } }$

$\green {\mathbf {\boxed { x_2 = -4} } }$

$\green {\mathbf {\boxed { S = x_1 = 5; x_2 = -4} } }$