Tham khảo tài liệu 'math test english 4', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ACT MATH TEST PRACTICE Use a test number in each region to see if x 3 x - 2 is positive or negative in that region. numbers less than -3 test -5 -5 3 -5 - 2 14 positive numbers between -3 and 2 test 0 0 3 0 - 2 -6 negative numbers greater than 2 test 3 3 3 3 - 2 6 positive The original inequality was x 3 x - 2 0. If a number is less than zero it is negative. The only region that is negative is between -3 and 2 -3 x 2 is the solution. Functions Functions are often written in the form f x 5x - 1. You might be asked to find f 3 in which case you substitute 3 in for 3 5 3 - 1. Therefore f 3 14. Matrices Basics of 2 X 2 Matrices Addition a11 a12i rb11 b12 La21 a22i Lb21 b22 J a11 b11 a12 b12 -a21 b21 a22 b22. Subtraction Same as addition except subtract the numbers rather than adding. Scalar Multiplication a11 a12 -a21 a22. ka11 ka12 -ka21 ka22. Multiplication of Matrices a11 a12 a21 a22 b11 b12 b21 b22 a11 b11 a12 b21 . a21 b11 a22 b21 a11 b12 a12 b22 a21 b12 a22 b22- k Coordinate Geometry This section contains problems dealing with the x y coordinate plane and number lines. Included are slope distance midpoint and conics. Slope The formula for finding slope given two points x1 y1 and x2 y2 is x2 -X The equation of a line is often written in slope-intercept form which is y mx b where m is the slope and b is the y-intercept. Important Information about Slope A line that rises to the right has a positive slope and a line that falls to the right has a negative slope. A horizontal line has a slope of 0 and a vertical line does not have a slope at all it is undefined. Parallel lines have equal slopes. Perpendicular lines have slopes that are negative reciprocals. 159 ACT MATH TEST PRACTICE Distance The distance between two points can be found using the following formula d V 2 - x1 2 y2- y1 2 Midpoint The midpoint of two points can be found by taking the average of the x values and the average of the y values. J_ ._ X1 X2 T1 2 midpoint 2 2 Conics Circles ellipses .
