What is the general solution for tan^2(x)+3sec(x)=-3 ?

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

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tan^2(x)+3sec(x)=-3

Solution

tan^{2} (x) + 3 sec (x) = - 3

Solution

x = π + 2 πn, x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

Degrees

x = 18 0^{\circ} + 36 0^{\circ} n, x = 12 0^{\circ} + 36 0^{\circ} n, x = 24 0^{\circ} + 36 0^{\circ} n

Solution steps

tan^{2} (x) + 3 sec (x) = - 3

Subtract

- 3

from both sides

tan^{2} (x) + 3 sec (x) + 3 = 0

Rewrite using trig identities

3 + tan^{2} (x) + 3 sec (x)

Use the Pythagorean identity:

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

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

= 3 + sec^{2} (x) - 1 + 3 sec (x)

Simplify

3 + sec^{2} (x) - 1 + 3 sec (x) : sec^{2} (x) + 3 sec (x) + 2

3 + sec^{2} (x) - 1 + 3 sec (x)

Group like terms

= sec^{2} (x) + 3 sec (x) + 3 - 1

Add/Subtract the numbers:

3 - 1 = 2

= sec^{2} (x) + 3 sec (x) + 2

= sec^{2} (x) + 3 sec (x) + 2

2 + sec^{2} (x) + 3 sec (x) = 0

Solve by substitution

2 + sec^{2} (x) + 3 sec (x) = 0

Let:

sec (x) = u

2 + u^{2} + 3 u = 0

2 + u^{2} + 3 u = 0 : u = - 1, u = - 2

2 + u^{2} + 3 u = 0

Write in the standard form

a x^{2} + b x + c = 0

u^{2} + 3 u + 2 = 0

Solve with the quadratic formula

u^{2} + 3 u + 2 = 0

Quadratic Equation Formula:

For

a = 1, b = 3, c = 2

u_{1, 2} = \frac{- 3 \pm 3 ^{2} - 4 \cdot 1 \cdot 2}{2 \cdot 1}

u_{1, 2} = \frac{- 3 \pm 3 ^{2} - 4 \cdot 1 \cdot 2}{2 \cdot 1}

3^{2} - 4 \cdot 1 \cdot 2 = 1

3^{2} - 4 \cdot 1 \cdot 2

Multiply the numbers:

4 \cdot 1 \cdot 2 = 8

= 3^{2} - 8

3^{2} = 9

= 9 - 8

Subtract the numbers:

9 - 8 = 1

= 1

Apply rule

1 = 1

= 1

u_{1, 2} = \frac{- 3 \pm 1}{2 \cdot 1}

Separate the solutions

u_{1} = \frac{- 3 + 1}{2 \cdot 1}, u_{2} = \frac{- 3 - 1}{2 \cdot 1}

u = \frac{- 3 + 1}{2 \cdot 1} : - 1

\frac{- 3 + 1}{2 \cdot 1}

Add/Subtract the numbers:

- 3 + 1 = - 2

= \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 = \frac{- 3 - 1}{2 \cdot 1} : - 2

\frac{- 3 - 1}{2 \cdot 1}

Subtract the numbers:

- 3 - 1 = - 4

= \frac{- 4}{2 \cdot 1}

Multiply the numbers:

2 \cdot 1 = 2

= \frac{- 4}{2}

Apply the fraction rule:

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

= - \frac{4}{2}

Divide the numbers:

\frac{4}{2} = 2

= - 2

The solutions to the quadratic equation are:

u = - 1, u = - 2

Substitute back

u = sec (x)

sec (x) = - 1, sec (x) = - 2

sec (x) = - 1, sec (x) = - 2

sec (x) = - 1 : x = π + 2 πn

sec (x) = - 1

General solutions for

sec (x) = - 1

sec (x)

periodicity table with

2 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} sec (x) 1 \frac{2 3}{3} 22 Undefined - 2 - 2 - \frac{2 3}{3} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sec (x) - 1 - \frac{2 3}{3} - 2 - 2 Undefined 22 \frac{2 3}{3}

x = π + 2 πn

x = π + 2 πn

sec (x) = - 2 : x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

sec (x) = - 2

General solutions for

sec (x) = - 2

sec (x)

periodicity table with

2 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} sec (x) 1 \frac{2 3}{3} 22 Undefined - 2 - 2 - \frac{2 3}{3} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sec (x) - 1 - \frac{2 3}{3} - 2 - 2 Undefined 22 \frac{2 3}{3}

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

Combine all the solutions

x = π + 2 πn, x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

Popular Examples

csc(x)=-(2sqrt(3))/3

csc (x) = - \frac{2 3}{3}

sin(2x)=-5cos(2x),0<= x<= 2pi

sin (2 x) = - 5 cos (2 x), 0 \leq x \leq 2 π

2cos^2(x)+9cos(x)-5=0

2 cos^{2} (x) + 9 cos (x) - 5 = 0

cos(θ)=-(sqrt(3))/4

cos (θ) = - \frac{3}{4}

tan(θ)=(sqrt(3))/2

tan (θ) = \frac{3}{2}

Frequently Asked Questions (FAQ)

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