How do you solve $x^2 - 361 = 0$ ?

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Answer 1 · 2016-05-19T16:24:56

Solution as the primary root is $x=19$

Add $color(blue)(361)$ to both sides

$color(brown)(x^2-361color(blue)(+361)" "=" "0color(blue)(+361)$

But -361+361=0

$x^2+0=361$

Square root both sides

$sqrt(x^2)=sqrt(361)$

As 361 is in the hundreds then the root involves 10 as 10^2=100 so the root is something like $(10+?)^2$

The last digit of 361 is 1 and $9xx9=81$ so trying $(10+9)^2$ proves to be the square root. However $(-19)xx(-19)=(+19)xx(+19) = + 361$

$x=+-19$

There is something called the primary root which is always positive

Solution as the primary root is $x=19$

How do you solve x^2 - 361 = 0x^2 - 361 = 0?