What are the solutions to the equation 90=2r^2+8r ?

The solutions to the equation 90=2r^2+8r are r=5,r=-9

Find the zeros of 90=2r^2+8r

The zeros of 90=2r^2+8r are r=5,r=-9

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

90 = 2 r^{2} + 8 r

r = 5, r = - 9

Solution steps

90 = 2 r^{2} + 8 r

Switch sides

2 r^{2} + 8 r = 90

Move

90

to the left side

2 r^{2} + 8 r - 90 = 0

Solve with the quadratic formula

r_{1, 2} = \frac{- 8 \pm 8 ^{2} - 4 \cdot 2 ( - 90 )}{2 \cdot 2}

8^{2} - 4 \cdot 2 (- 90) = 28

r_{1, 2} = \frac{- 8 \pm 28}{2 \cdot 2}

Separate the solutions

r_{1} = \frac{- 8 + 28}{2 \cdot 2}, r_{2} = \frac{- 8 - 28}{2 \cdot 2}

r = \frac{- 8 + 28}{2 \cdot 2} : 5

r = \frac{- 8 - 28}{2 \cdot 2} : - 9

The solutions to the quadratic equation are:

r = 5, r = - 9

49 x^{2} - 14 x + 1

x^{6} - y^{4}

7 k^{2} + 9 k

10 + x = 100 - 0.005 x

\frac{3 ( x + 2 )}{4} = 2 x - 1

What are the solutions to the equation 90=2r^2+8r ?
The solutions to the equation 90=2r^2+8r are r=5,r=-9
Find the zeros of 90=2r^2+8r
The zeros of 90=2r^2+8r are r=5,r=-9