holy moly no need to post this 20 times :P
so the problem is you can't add or subtract radicals that aren't the same, so you have to modify them so that you have the same numbers inside the radicals
the easiest way to visualize this sort of thing is to break all the numbers down to their primes
28=7*2*2
175=5*5*7
7=7
(to do this easily just keep dividing by larger primes until you can't anymore, starting with 2, then 3,5,7 etc)
so root(7*2*2)+root(5*5*7)-root(7)
now when you have numbers multiplying each other inside a radical like that, you can rewrite it like this
root(7)*root(2*2)+root(7)*root(5*5)-root(7)
and when the same number multiplies itself inside a root like root(2*2) it just cancels the root. (i.e. 2*2 is 4 and the square root of 4 is 2)
so now we have 2*root(7)+5*root(7)-root(7)
now all the roots are the same so you can add them and subtract them easily.
if this is hard to imagine, just pretend that root(7)=x such that
2x+5x-x
or 6x
but x=root(7)
so 6*root(7) the answer!
hope this helps
In math we're doing a review sheet and i don't get any of it so can someone please help!!
What is the simplest form of the expression Radical 28 + radical 175 - radical 7
1 answer