contestada

Solve x2 − 3x = −8.



x equals quantity of 3 plus or minus I square root of 29 all over 2


x equals quantity of 3 plus or minus I square root of 23 all over 2


x equals quantity of negative 3 plus or minus I square root of 29 all over 2


x equals quantity of negative 3 plus or minus I square root of 23 all over 2

Respuesta :

we have

[tex]x^{2} -3x=-8[/tex]

Complete the square. Remember to balance the equation by adding the same constants to each side

[tex]x^{2} -3x+1.5^{2}=-8+1.5^{2}[/tex]

[tex]x^{2} -3x+1.5^{2}=-5.75[/tex]

Rewrite as perfect squares

[tex](x-1.5)^{2}=-5.75[/tex]

Square Root both sides

[tex]x-1.5=(+/-)\sqrt{-5.75}[/tex]

Remember that

[tex]\sqrt{-1}=i[/tex]

[tex]\sqrt{5.75}= \sqrt{\frac{23}{4}}=\frac{\sqrt{23}}{2}[/tex]

Substitute

[tex]x-1.5=(+/-)i\frac{\sqrt{23}}{2}[/tex]

[tex]x=1.5(+/-)i\frac{\sqrt{23}}{2}[/tex]

[tex]x=(3/2)(+/-)i\frac{\sqrt{23}}{2}[/tex]

[tex]x=(3/2)+i\frac{\sqrt{23}}{2}=\frac{3+i\sqrt{23}}{2}[/tex]

[tex]x=(3/2)-i\frac{\sqrt{23}}{2}=\frac{3-i\sqrt{23}}{2}[/tex]

therefore

the answer is

x equals quantity of 3 plus or minus I square root of 23 all over 2