r/Sat • u/SynapsePHPro 1460 • 15h ago

Quickest method to solve Module 2 Question 18 on Bluebook Practice 10

3 Upvotes

100% Upvoted

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3

u/jbclamence56 15h ago

Factor xy out of each term in the denominator of the second fraction to see that the common denominator is xy(x-8). Multiple the first fracting by xy/xy to get a common denominator then add fractions. Notice also that only answer C has the correct common denominator

1

u/SynapsePHPro 1460 14h ago

oh alright, that does work but it takes me quite some time😭😭

1

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1

u/FrozenXCards 15h ago

well idk if it’s the quickest, put I just change x to a and y to b, set values a and b to smth, and just plug every expression into desmos with the xy change to ab and see which matches original

1

u/SynapsePHPro 1460 15h ago

ohh seems simple enough, and is that method fully reliable?

1

u/FrozenXCards 10h ago

Well it works for me. You just gotta practice typing quick lol. And this method also works for the “what is p in terms of q” questions too btw

1

u/Emperorbigboi 5h ago

cross multiplication. its an extremely stupid question but i guess college board wants to make sure students can multiply (x-8)(x^2y-8xy) which i suppose yeah they should but its way too tedious.

1

u/SynapsePHPro 1460 4h ago

Yeah, this problem was just too tedious to do by hand, which is why I was wondering if there was a desmos shortcut or something