 Simultaneous Equations - Quiz 1 Question Question 1 Solve the system simultaneous equations below
 x + y = 4 (1) x - y = 6. (2)
Which of the following is the value of x?
 a) x = 10. b) x = -1. c) x = 2. d) x = 5.

Not correct. Choice (a) is false.
Try again. You need to add the equations together to eliminate y .
Not correct. Choice (b) is false.
Try again. You need to add the equations together to eliminate y .
Not correct. Choice (c) is false.
Try again. You need to add the equations together to eliminate y .
Solving by elimination we add the two equations and get 2x = 10 and hence x = 5. This then gives y = -1 since y = 4 -x = 4 - 5 = -1 and we check (2) and see that 5 - (-1) = 6. So we have that x = 5.
 Question 2 Solve the system simultaneous equations below (1) (2)
Which of the following is the value of a) b) c) d) Not correct. Choice (a) is false.
Try again. You need to multiply equation (1) by 2 and subtract the equations to eliminate Not correct. Choice (b) is false.
Try again. You need to multiply equation (1) by 2 and subtract the equations to eliminate Not correct. Choice (c) is false.
Try again. You need to multiply equation (1) by 2 and subtract the equations to eliminate Multiply equation (1) by 2 to give (3)
and subtract equation (2) from (3) we get Substituting into (1) we get so Check in (2) and 2(2)-(-3)=4+3=7 and we have and Question 3 Consider the simultaneous equations below
 5x + 2y = 9 (1) 9x - 7y = -5. (2)
Which of the following are the correct steps to eliminate x from the equations?
 a) Multiply equation (1) by 7 and (2) by 2 and add the equations. b) Multiply equation (1) by 9 and (2) by 5 and subtract the equations. c) Multiply equation (1) by 7 and (2) by 2 and subtract the equations. d) Multiply equation (1) by 9 and (2) by 5 and add the equations.

Not correct. Choice (a) is false.
Try again, this eliminates y .
This then gives us
 45x + 18y = 81 45x - 35y = -25.
When we subtract one from the other we get 53y = 106 and y = 2.
Not correct. Choice (c) is false.
Try again, you seem to be trying to eliminate y .
Not correct. Choice (d) is false.
Try again, this would not eliminate x but give us 90x - 17y = 56.
 Question 4 Solve the system of simultaneous equations below
 5m - 6n = 12 (1) 2m + 9n = 20. (2)
Which of the following is the value of n?
 a) n = . b) n = -2. c) n = 2. d) n = -7.

Solving by elimination we multiply (1) by 2 and (2) by 5.
 10m - 12n = 24 (3) 10m + 45n = 100 (4)
Subtract equations (4) from (3) and get 57n = 76 so
n = = = .
Substitute n = into equation (1) and get 5m- 6( ) = 12 so 5m = 12 + 8 = 20, so m = 4.
Check in equation (2), and 2(4) + 9( ) = 8 + 12 = 20 and we have m = 4 and n = .
Not correct. Choice (b) is false.
Try again. To solve by elimination we multiply (1) by 2 and (2) by 5.
Not correct. Choice (c) is false.
Try again. To solve by elimination we multiply (1) by 2 and (2) by 5.
Not correct. Choice (d) is false.
Try again. To solve by elimination we multiply (1) by 2 and (2) by 5.
 Question 5 Solve the system of simultaneous equations below = 9 (1) = 9. (2)
Which of the following is the value of w ?
 a) w = 1. b) w = 10. c) w = 8. d) w = 3.

Not correct. Choice (a) is false.
Try again. To solve by elimination we multiply (1) by 2 and (2) by 5 to eliminate the fractions.
Not correct. Choice (b) is false.
Try again. To solve by elimination we multiply (1) by 2 and (2) by 5 to eliminate the fractions. (5)