1. Test 4 Sample Math 123a
Solve the following system
a. by substitution b. by elimination
x=6+y x –y =6
x + 2y = - 3 x + 2y = -3
Solve the following systems by any method
A. x + y = 6 B. y = 4 + x C. 3x – 2y = 3
x–y=2 x + 2y = 6 4x – 3y = -1
Simplify
1. 3x + 7(2x – 5) 2. 3(x + 7) – 2(3 – 4x)
3. 3x(4x2 – 2x + 1) – 4x2(5 – 3x) 4. 2x(xy – x) + x2(3 – 5y)
5. (3x + 7)(2x – 5) 6. (2x + 5)(x – 2) + (x – 1)(3x + 2 )
7. (3x – 5 ) 2 8. (4x – 5)(4x + 5)
9. (2x –3)(x + 1) – (4x – 3)(x – 1) 10. (2x + 3)(x – 3) – (2x – 3)2
11. a. Evaluate –2x2y – 3xy2 if y = –2. b. Evaluate –2x2y – 3xy2 at (3, –2).
12. Let x = price / lb of peanuts, y = price / lb for cashews. Find x and y given the following invoice.
Order 1. (in lb) Order 2 (in lb)
Cashews 2 3
Peanuts 3 1
Cost $16 $16
13. Peanuts costs $2/lb, cashews costs $8/lb. How many lbs of each are needed to get 50 lbs of
peanut–cashews–mixture that cost $3/lb? Write down what x and y represent and make a table.
14. We have $8,000 in two accounts, one at 8% and the other at 6%. Their combined interest is $600. How
much is in each account?
15. A. Calculate and leave the answer B. Calculate and leave the answer
as a reduced fraction 40 * 3 – 3 * 2 2 as a reduced fraction 40 * 3-1 – 3 * 2 -2
16. A. Write the number 2,340,000,000 in B. Convert 3.76 x 10 -5 into a decimal
the scientific notation
C. compute 2.3x1060 x 8.9 x10-38 and put the answer in the scientific notation
17. Simplify and leave the answer in positive exponent:
2 4 2 4
21 x y x y
A. 5 2
B. 5 2
14 x y x y