Question

How do you solve `-7n^2=-448`?

Answer 1

`n=+-8`

Explanation:

Divide both sides by -7 so as to isolate the `n^2` term.

`(cancel(-7)^1 n^2)/cancel(-7)^1=(cancel(-448)^(64))/cancel(-7)^1rArrn^2=64`

now take the square root of both sides

`sqrt(n^2)=+-sqrt64rArrn=+-8`

Answer 2

`n= 8 or n = -8`

Explanation:

This is a quadratic equation, it can be solved by factorising.

`-7n^2 = -448 larr div" "-7` to simplify. Divide on both sides.

`n^2 = 64 larr` make it =0

`n^2 -64 larr` difference of two squares.

`(n+8)(n-8) = 0`

Either factor can be equal to 0.

If `n+8 = 0 rarr n = -8`

If `n-8 = 0 rarr n = 8`