What are the solutions to the equation x(x+1)=21 ?

The solutions to the equation x(x+1)=21 are x=(-1+sqrt(85))/2 ,x=(-1-sqrt(85))/2

Find the zeros of x(x+1)=21

The zeros of x(x+1)=21 are x=(-1+sqrt(85))/2 ,x=(-1-sqrt(85))/2

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x (x + 1) = 21

x = \frac{- 1 + 85}{2}, x = \frac{- 1 - 85}{2}

Solution steps

x (x + 1) = 21

Expand

x (x + 1) : x^{2} + x

x^{2} + x = 21

Move

21

to the left side

x^{2} + x - 21 = 0

Solve with the quadratic formula

x_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 \cdot 1 \cdot ( - 21 )}{2 \cdot 1}

1^{2} - 4 \cdot 1 \cdot (- 21) = 85

x_{1, 2} = \frac{- 1 \pm 85}{2 \cdot 1}

Separate the solutions

x_{1} = \frac{- 1 + 85}{2 \cdot 1}, x_{2} = \frac{- 1 - 85}{2 \cdot 1}

x = \frac{- 1 + 85}{2 \cdot 1} : \frac{- 1 + 85}{2}

x = \frac{- 1 - 85}{2 \cdot 1} : \frac{- 1 - 85}{2}

The solutions to the quadratic equation are:

x = \frac{- 1 + 85}{2}, x = \frac{- 1 - 85}{2}

- 4 x^{2} - 16 x - 12

6 x - 8 = 5 x + 4

y^{6} - x^{6}

x^{2} - 4 x + 85 = 0

z^{2} - x^{2}

What are the solutions to the equation x(x+1)=21 ?
The solutions to the equation x(x+1)=21 are x=(-1+sqrt(85))/2 ,x=(-1-sqrt(85))/2
Find the zeros of x(x+1)=21
The zeros of x(x+1)=21 are x=(-1+sqrt(85))/2 ,x=(-1-sqrt(85))/2