View Full Version : Adding and subtracting radical expressions
dingolove09
Mar 16, 2009, 02:31 PM
yes this is my homework... v.v..
1) √63 + √175 + √112
2) √28x + √63x
3) √45 + √180
4) √52 - √1300
5) 5√98 - 3√32
6) √32 + √128
7) √147 + 6√3
8) √168 + √42
9) 5√17 + 17√5
10) 6√3 + √300
11) -2√3b + √27b
12) 4√2m + 6√3m - 4√2m
13) √50m + √72m
14) √16z + 2√8z - 3√z
15) √216t + √96t
16) 4√52x + √117x - 2√13
17) 3√96k + 2√180
jordan1989
Mar 16, 2009, 02:48 PM
You need to factor the radicand of each radical down to the prime factorization. If you get a pair of factors, pull it outside the radicand as a coefficient. Add the coefficients.
dingolove09
Mar 16, 2009, 02:52 PM
I'll try it, I get lost when it comes to coefficients
jordan1989
Mar 16, 2009, 02:53 PM
Try the first problem, and post the answer here. I'll let you know if you've done it correctly or not.
dingolove09
Mar 16, 2009, 03:05 PM
√63 + √175 + √112
√3*21 √5*35 √4*28
3√21 5√35 4√28
Am I right so far?. I don't know
jordan1989
Mar 16, 2009, 03:12 PM
You're right so far, but you need the prime factorization. You should end up with the same radicand, so they can be added.
Let me complete the first one for you, so you can see how it's done:
We have √63 + √175 + √112
√63 = √3 X 3 X 7. There's a pair of 3's and a 7 left over, so pull out the 3 to make 3√7
√175 = √5 X 5 X 7. There's a pair of 5's and a 7 left over, so pull out the 5. 5√7
√112 = √2 X 2 X 2 X 2 X 7. We have 2 pairs of 2's, so that becomes 4. 4√7
3 + 5 + 4 = 12. So the final answer is 12√7
dingolove09
Mar 16, 2009, 03:20 PM
So I just need to find the prime factorization of the radicands?
jordan1989
Mar 16, 2009, 03:24 PM
Yes, that's all you need to do. Pair up any pairs of factors and pull them out, and anything left over (singles)would be left under the radicand.
dingolove09
Mar 16, 2009, 03:27 PM
Oh OK, well thank you