The average of 6 quiz scores, where 
is the score of the last quiz, is
The student needs a minimum average of 86 to earn an A:
so the student needs a score of 91.
Answer:
Step-by-step explanation:
1) 2x + y = 3 -(1)
-3x + 2y = -8 -(2)
(1) x 2 => 4x + 2y = 6 -(3)
(3) - (2)
=> 4x + 2y + 3x - 2y = 6 + 8
=> 7x = 14
=> x = 2
=> 2(2) + y = 3
=> y = 3 - 4 = -1
2) 6x + 7y = -9 -(1)
-4x - 5y = 5 -(2)
(1) x 4 => 24x + 28y = -36 -(3)
(2) x 6 => -24x - 30y = 30 -(4)
(3) + (4)
=> 24x + 28y - 24x - 30y = -36 + 30
=> -2y = -6
=> y = 3
=> 6x + 7(3) = -9
=> 6x = -30
=> x = -5
3) -x - 7y = 9 -(1)
-x + 9y = -23 -(2)
(1) - (2)
=> -x - 7y + x - 9y = 9 + 23
=> -16y = 32
=> y = -2
=> -x - 7(-2) = 9
=> -x = -23
=> x = 23
4) -x + 9y = -5 -(1)
x - 5y = 1 -(2)
(1) + (2)
=> -x + 9y + x - 5y = -5 + 1
=> 4y = -4
=> y = -1
=> x - 5(-1) = 1
=> x = -5
5) -2x + y = 10 -(1)
4x + y = -14 -(2)
(1) - (2)
=> -6x = 24
=> x = -4
=> 4(-4) + y = -14
=> y = -14 + 16 = 2
X cannot equal +2, and can't be -1. If you factor it, then you notice you get 2(x+2)(x-2). If you use either one for the x, one will be zero and the won't, and vise-versa.
Answer:
i thinkbit is C but im in 6th grade and at may 5 i. not there yet
