two SAT math problems

Test Preparation SAT Preparation
1

<p>SO here they are :)
<a href="http://img197.imageshack.us/img197/7585/barb.gif%5B/url%5D"&gt;http://img197.imageshack.us/img197/7585/barb.gif&lt;/a>
<a href="http://img197.imageshack.us/img197/705/const.gif%5B/url%5D"&gt;http://img197.imageshack.us/img197/705/const.gif&lt;/a&gt;&lt;/p>

2

<p>the second one is A. 8.</p>

<p>u realize that t must be 3 for the last number to equal 15. then you foil it out and see what the k turns out to be ( 8 ).</p>

3

<p>The first one is C.</p>

<p>She buys d dollars worth of gas, and a gallon of gas is $1.25, so d divided by 1.25 gives the amount in gallons that she bought. Then simply subtract that from 2 since her tank holds 2 gallons and she filled it all the way. So:</p>

<p>2 - (d / 1.25)</p>

4

<p>For the second one - plug in x=-5.</p>

5

<p>Thanks for the idea to plug in x=-5, gcf101… I never thought of that.
I did it the way Lewd did, by figuring out that in order for it to be 15, t had to be 3. Then, k had to be 8, but your method is much faster and more efficient. I will have to remember this for future practice!
It’s easier to set the equation equal to 0 then solve.</p>

6

<p>My pleasure!</p>

<p>Unfortunately, on the real SAT, most of the time, questions of this type do require two-step approach.
Knowing Vieta’s Theorem
<a href=“http://eqworld.ipmnet.ru/en/solutions/ae/ae0102.pdf[/url]”>http://eqworld.ipmnet.ru/en/solutions/ae/ae0102.pdf&lt;/a&gt;
saves a bit of time.</p>

<p>I don’t recall seeing equations other than with a=1;
you have then
x1+x2 = -b
(x1)(x2)= c.</p>

<p>This fact proved priceless on the SAT Math 2 in May.
Q.48 If s and t are the roots of
x^2 - 6x + 1 = 0,
which of the following equations would have roots
s-1 and t-1?
(I changed the question a little).</p>