Squaring a binomial with radicals

10/5/2011

How do you square this?
(√3+√5)²

= (√3 + √5)(√3 + √5) {when squaring a binomial, multiply it by itself}
= √3 (√3) + √3 (√5) + √5 (√3) + √5 (√5) {used foil method}
= √9 + √15 + √15 + √25 {multiplied through}
= 3 + 2√15 + 5 {evaluated square roots}
= 8 + 2√15 {combined like terms}

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2 Comments

greg capito link

10/10/2012 06:09:22 am

Why are rules for squaring a binomial different from squaring a radical?
example: (3x+4)squared as opposed to square root of 3x+4 squared.

Algebra House link

10/10/2012 06:48:56 am

When squaring a radical, you simply remove the square root sign:

Example:
[√(3x + 2)]²
= 3x + 2 {when you square the square root of an expression, it is simply the expression, itself}

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