Below are the 2016 Grade 9 Math Challenge – Elimination Round questions and answers – Part I. More reviewers can be found on the **Past Tests** and **All Posts** pages.

1.) Solve for *x* in .

2.) Find if and

3.) What is the value of

4.) Solve for *x* in

5.) Solve for *x* in .

6.) Find the sum of the first 20 positive odd numbers.

7.) Solve for *x* in

8.) Find all possible values of *x* if one of the interior angles of a square is

9.) What is the sum of the interior angles of a pentagon?

10.) The supplement of an angle is four times its complement. Find the angle.

11.) What is the shortest side of and

12.) Rationalize the denominator and simplify:

13.) Find the 25th term of the arithmetic sequence whose first 3 terms are 4, 7, and 10.

14.) Solve for *x* in

15.) For what value/s of *x* is

16.) In and Determine the value of tan *C*.

17.) The angle bisector at vertex B of meets *AC* at *D*. If *BC* = 6, *AC* = 40,and *CD* = 15, find *AB*.

18.) Find the equation of the line parallel to and passing through (-12, 4).

19.) Express in terms of sines or cosines of and simplify:

20.) Find the common ratio of a geometric sequence whose first term is -2 and the 7th term is -1458.

21.) Solve for *x* in

22.) Find the 7th term of the geometric sequence 8, 12, 18, …

23.) Triangle ABC is a righttriangle with . If and , find b.

24.) Two of the exterior angles of a regular polygon measure and . How many sides does this regular polygon have?

25.) Solve for *x* in:

Answer key:

1.) -14

2.)

3.)

4.) 0 or 3

5.)

6.) 400

7.) 3 < *x* < 4

8.) -5, 9

9.)

10.)

11.) PQ

12.)

13.) 76

14.) 0 or 4

15.) all real numbers or

16.)

17.) 10

18.) 4x + 3y = -36

19.)

20.)

21.)

22.)

23.)

24.) 15

25.) 2

View Part II here: 2016 Grade 9 Math Challenge – Elimination Round with answer key – Part II