Sat_数学考试试题(19)

Sat 数学历年真题

= 30

2

problem take 15 seconds at most to solve.

* FOILing is when we take 2 expressions like (x+2) and (x-2) and multiply them out. First: x × x + Outside: x × (-2) + Inside: 2 × (x) + Last: 2×(-2) First: x2 + Outside: -2x + Inside: 2x + Last: -4 Equation: x2+ -2x + 2x + -4

Simplify: x2 + -2x + 2x + -4 (-2x + 2x = 0. Get rid of those terms.) = x2-4

Test 1 Section 3 Question 15

Geometry and Algebra Problem. Lots of variables (friends).

There are a ton of variables in this problem, or at least letters, A, O, B, x, y, p, r. Let’s write our givens:

(p, r) are the coordinates of point A.

|p| > |r|. The absolute value (no signs) of p is greater than r. Now put those two nuggets aside for a second.

What are we looking for? The slope of AB. iii

Before doing anything further, look at the line and the answers. What are those answers? They are potential slopes of that line; that’s what we’re looking for, the slope of AB. Does the slope look positive or negative? Remember:

iv

Which graph looks like the one in the problem? It looks like a negative slope. So answers C, D & E are out. If we get no further, guess, because we’ve got a 50/50 shot of being correct.

We are left with two options answers A (-2) and B (½). Let’s try both.