Use the quadratic formula to solve the equation `5r^2-22=0.`

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degeneratecircle | High School Teacher | (Level 2) Associate Educator

Posted on

We need to write `5r^2-22=0` in the form `ar^2+br+c=0,` so `a=5, b=0,` and `c=-22.` The rest is just plugging in. According to the quadratic formula, the two solutions are given by

`(-0+-sqrt(0^2-4*5*(-22)))/(2*5)=(+-sqrt(440))/10=+-sqrt(110)/5.`

The solutions are `r_1=sqrt(110)/5` , `r_2=-sqrt(110)/5.`

 

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durbanville | High School Teacher | (Level 2) Educator Emeritus

Posted on

The solutions are ,

Simplfy this because 110 = is 2x2x2x13

= `(sqrt(2^2 times 2 times 13))/5`

= `(2sqrt(2. times 13))/5`  or `(-2sqrt (2 times 13))/5`

= `(2sqrt26)/ 5 or (-2sqrt26)/5`

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