<p>Hello, these are the math problems that I need help with: (Blue Book, Test 5, Section 7)</p>
<p>18)If the sum of the consecutive integers from -22 to x, inclusive, is 72, then what is x?
a) 23
b) 25
c) 50
d) 75
e) 94</p>
<p>19)If k, n,x and y are positive numbers satisfying x^-4/3 = k^-2 and y^4/3 = n^2, what is (xy)^-2/3 in terms of n and k?
a)1/nk
b) n/k
c) k/n
d) nk
e) 1</p>
<p>20) Has graphs and crap so I can't type it out.</p>
<p>for 20, take a point on each graph
f(x) (-1,3) and g(x) would be (2,1)</p>
<p>how do you get from -1 to 2? you are moving RIGHT 3 so you have to subtract 3 (-3).
how do you get from 3 to 1? you are moving DOWN 2 so you have to subtract 2 (-2)</p>
<p>Q.8 - The sum of the numbers is positive so x will have to be greater than 22 because in order to cancel out -22 you’ll need a 22 similarly to cancel the -21 you’ll need a 21 and so on.So the sum from -22 to 22 will be 0.after that you continue to add the next numbers until you get the desired sum.i.e. 23+24=47+25=72. The last number you added was 25 so x =25.</p>
<p>Thanks everybody for the responses, they really helped. The only one I still don’t understand is #20. Would somebody mind trying to explain this thoroughly with the thought process? Thanks again.</p>
<p>excuse me but in the USA don’t you study aritmetical and geometrical progressions? What are that stupid solutions for 18?! If you have that the sum of all integers between 23 and x is 1245 what would you do?!</p>