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23 votes
23 votes
Okay hopefully the picture went but I need help foiling this please

Okay hopefully the picture went but I need help foiling this please-example-1
User TanmayP
by
2.6k points

1 Answer

17 votes
17 votes

Answer:


x^(2) -
z^(2) - 2z
√(5) - 5

Explanation:

This is the equation that you started off with:

(x - z -
√(5))(x + z +
√(5))

You can't really use FOIL on this because that's used in multiplying binomials, and this is a trinomial, but you can still break it up and simplify it this way:

(a + b + c)*(d + e + f) = (a(d + e +f)) + (b(d + e + f)) + (c(d + e + f))

So, applying that idea to the actual equation:

x(x + z +
√(5)) -z(x + z +
√(5)) -
√(5)(x + z +
√(5))

= x^2 + xz + x
√(5) -xz -z^2 - z
√(5) - x
√(5) - z
√(5) - 5

= x^2 - z^2 - 2z
√(5) - 5

or
x^(2) - z^(2) - 2z√(5) - 5

User Pramod Alagambhat
by
3.4k points