heartonsleeve

Hey, can someone help me out? I can't quite figure out #12, 13, or 14 from the blue book, pg 339 and 340. Thanks in advance. (and sorry for the mistake in the thread title!!)

ny10804

What is this blue book everyone talks about?

heartonsleeve

It's the Official SAT Study Guide by College Board.

DukeofFunk

Dunno if you need help, but as far as I can tell for 12 you have to do the problem with the rule that two sides of a triangle are always greater than the third side in mind. 3, 4, and 5 wouldn't work because they're all less than or equal to 7, but 6 would. Therefore, the answer is one possible triangle.

For 13, I can't figure out any quick way to do it besides actually solving for x (-1, -5) and y (5, -7) and then adding all the possible numbers and knowing that 10 doesn't exist. There's probably a quicker way to do this, but I'm just too stupid.

For 14, since a multiplied by (b-a) is 0, then a must be 0. It wouldn't matter whats in the parentheses, because whatever it's multiplied by makes it 0, and since a is the number on the outside, it must be 0. Since a is greater than b, and a is 0, b must be less than 0. If b is less than 0, and a is 0, then a-b will be > than 0 because the two negatives would cancel out. Like, if b was -3, it would be 0-(-3), or 0+3, which would make it greater than 0. So all three statements are true

Did that help? Did you still need help? Am i too late? Is this confusing for you? Sorry. I hope I helped.

heartonsleeve

Thank you!!! Yes, I did still need help.

I got 12 and 14 but I still don't understand 13. ^^;;
Could you explain that again?

DukeofFunk

Ok, well to solve the problem the long way, solve each equation individually. Get the abs value sign by itself, so

|x+3| = 2
|y+1| = 6

Since they're both within absolute value signs, you have to set equations for both positive and negative. So it'd be like

x+3 = 2 AND x+3=-2

ditto with the y equation. For x, that'll get you -1 and -5. For y, you'll get 5 and -7. Then since it's asking for all the possible x+y's, you add the different combinations together (-1 + 5, -5 + 5, -7 + -1, and -7 +-5) and take the absolute value of the number. So it'd be 4, 0, 8, and 12. You can't come up with 10, so that's the answer.

There's probably a simpler way to do this, but this is how I figured it out.

heartonsleeve

Thanks!! I really appreciate it

This is a really silly question, because I know I should know how to do this, but can you solve #7 on pg 361 for me? A similar problem came up in one of the next practice sets, and I couldn't figure out either.

Thanks a million!

DukeofFunk

The first set of points gives you the y intercept, making the equation y=1/4x + 1/2. Plug 4 from the other set into the equation, so 4(1/4) + 1/2 = 1 1/2.

heartonsleeve

Thank you!!! Again, I really, really appreciate it.