
Understandably, not many people like surds…
A surd is basically a number that when you square root it leaves you with a decimal.
So, for example, if we were looking to simplify √63:
1x63
(2 won’t work)
3 x21
(4 won't work)
(5 won't work)
(6 won't work)
7 x9
Seen as 7x9 is the only pair that involves a square number, we will go with that pair.
Square root the 9 and place that to the left of the surd sign, then sit the 7 underneath giving you the answer: 3√7
Once that bit is conquered, you can look at adding and subtracting surds.
If you were asked: √63 +√28 we already know that √63 is 3√7, so we just need to simplify √28.
The factor pairs of 28 are:
1x28
2x14
4x7
4x7 is the pair with the square number.
This gives you the question: 3√7 + 2√7
3+2 =5,
the 7 stays the same,
so the answer to our question is 5√7.
When you multiply surds you multiply the number on the outside by the number on the inside, so in another example we might have 3√2 x 5√7.
3x5 = 15, this goes on the outside 2x7 = 14, so this goes on the inside
To divide the principle is the same except instead of multiplying the numbers you divide.
But I hope this makes the initial steps seem easier to contend with.
