What is the general solution for tan^2(x)+2tan(x)=-1 ?

The general solution for tan^2(x)+2tan(x)=-1 is x=(3pi)/4+pin

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tan^2(x)+2tan(x)=-1

Solution

tan^{2} (x) + 2 tan (x) = - 1

Solution

x = \frac{3 π}{4} + πn

Degrees

x = 13 5^{\circ} + 18 0^{\circ} n

Solution steps

tan^{2} (x) + 2 tan (x) = - 1

Solve by substitution

tan^{2} (x) + 2 tan (x) = - 1

Let:

tan (x) = u

u^{2} + 2 u = - 1

u^{2} + 2 u = - 1 : u = - 1

u^{2} + 2 u = - 1

Move

1

to the left side

u^{2} + 2 u = - 1

Add

1

to both sides

u^{2} + 2 u + 1 = - 1 + 1

Simplify

u^{2} + 2 u + 1 = 0

u^{2} + 2 u + 1 = 0

Solve with the quadratic formula

u^{2} + 2 u + 1 = 0

Quadratic Equation Formula:

For

a = 1, b = 2, c = 1

u_{1, 2} = \frac{- 2 \pm 2 ^{2} - 4 \cdot 1 \cdot 1}{2 \cdot 1}

u_{1, 2} = \frac{- 2 \pm 2 ^{2} - 4 \cdot 1 \cdot 1}{2 \cdot 1}

2^{2} - 4 \cdot 1 \cdot 1 = 0

2^{2} - 4 \cdot 1 \cdot 1

Multiply the numbers:

4 \cdot 1 \cdot 1 = 4

= 2^{2} - 4

2^{2} = 4

= 4 - 4

Subtract the numbers:

4 - 4 = 0

= 0

u_{1, 2} = \frac{- 2 \pm 0}{2 \cdot 1}

u = \frac{- 2}{2 \cdot 1}

\frac{- 2}{2 \cdot 1} = - 1

\frac{- 2}{2 \cdot 1}

Multiply the numbers:

2 \cdot 1 = 2

= \frac{- 2}{2}

Apply the fraction rule:

\frac{- a}{b} = - \frac{a}{b}

= - \frac{2}{2}

Apply rule

\frac{a}{a} = 1

= - 1

u = - 1

The solution to the quadratic equation is:

u = - 1

Substitute back

u = tan (x)

tan (x) = - 1

tan (x) = - 1

tan (x) = - 1 : x = \frac{3 π}{4} + πn

tan (x) = - 1

General solutions for

tan (x) = - 1

tan (x)

periodicity table with

πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = \frac{3 π}{4} + πn

x = \frac{3 π}{4} + πn

Combine all the solutions

x = \frac{3 π}{4} + πn

Popular Examples

4csc^2(x)-2=0

4 csc^{2} (x) - 2 = 0

sin(2θ-pi/2)=-1,0<= θ<2pi

sin (2 θ - \frac{π}{2}) = - 1, 0 \leq θ < 2 π

18cos(x)-9sqrt(3)=0

18 cos (x) - 93 = 0

sqrt(2)sin(3θ)-1=0

2 sin (3 θ) - 1 = 0

cot^2(θ)+1= 3/4

cot^{2} (θ) + 1 = \frac{3}{4}

Frequently Asked Questions (FAQ)

What is the general solution for tan^2(x)+2tan(x)=-1 ?
The general solution for tan^2(x)+2tan(x)=-1 is x=(3pi)/4+pin