Can some1 answer or help me with these problems? I've been struggling with these equations 4 2 weeks now and still cant understand them. These are pratice problems that i have that i need to understand.These all need to be in order pair.
1) 3x - y = 10
-x + y = -4
a (3, -7)
b (-1, 3)
c (3, -1)
d(3, 1)
2) 3x - y = 9
2x + y = 6
a (3,0)
b (3,-18)
c (3,-1)
d (3,1)
3)-3x + y = -4
3x + y = -4
a (-4, 0)
b (4, 0)
c (0, 4)
d (0, -4)
4)2x – y = 4
3x + y = 1
a (1, 2)
b (-2, 1)
c (1, -2)
d (2, 1)
5) x + y = 10
x - y = 8
a (-1,11)
b (1,9)
c (9,1)
d(8,0)
6)3x - y = 9
2x + y = 6
a (3,0)
b (3,-18)
c (3,-1)
d (3,1)
these ones needs 2 be worked out.
7) 2a + 3b = -1
3a + 5b = -2
8)2x + 2y = -14
3x + y = -9
9)2x + 6y = 38
3x - 3y = -3
10)3x + 5y = 1
x + 4y = 5
11)x + y = -4
x - y = 2
12)x + y = 10
y = x + 8
13)3x + y = 5
4x - 7y = -10
14) y - 2x = -5
3y - x =5
2007-01-01 10:47:27 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
1)
3x - y = 10
-x + y = -4
2x = 6
x = 3
-3 + y = -4
y = -1
ANS : c. (3,-1)
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2)
This is a repeat question
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3)
-3x + y = -4
3x + y = -4
2y = -8
y = -4
-3x - 4 = -4
-3x = 0
x = 0
ANS : d. (0,-4)
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4)
2x – y = 4
3x + y = 1
5x = 5
x = 1
2(1) - y = 4
2 - y = 4
-y = 2
y = -2
ANS : c. (1,-2)
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5)
x + y = 10
x - y = 8
2x = 18
x = 9
9 + y = 10
y = 1
ANS : b. (1,9)
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6)
3x - y = 9
2x + y = 6
5x = 15
x = 3
3(3) - y = 9
9 - y = 9
-y = 0
y = 0
ANS : a. (3,0)
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7)
2a + 3b = -1
3a + 5b = -2
Multiply top by -3 and bottom by 2
-6a - 9b = 3
6a + 10b = -4
b = -1
2a + 3(-1) = -1
2a - 3 = -1
2a = 2
a = 1
ANS : (1,-1)
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8)
2x + 2y = -14
3x + y = -9
3x + y = -9
y = -3x - 9
2x + 2(-3x - 9) = -14
x + (-3x - 9) -7
x - 3x - 9 = -7
-2x = 2
x = -1
y = -3(-1) - 9 = 3 - 9 = -6
ANS : (-1,-6)
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9)
2x + 6y = 38
3x - 3y = -3
multipy the bottom by 2
2x + 6y = 38
6x - 6y = -6
8x = 32
x = 4
2(4) + 6y = 38
8 + 6y = 38
6y = 30
y = 5
ANS : (4,5)
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10)
3x + 5y = 1
x + 4y = 5
x + 4y = 5
x = -4y + 5
3(-4y + 5) + 5y = 1
-12y + 15 + 5y = 1
-7y = -14
y = 2
x = -4(2) + 5 = -8 + 5 = -3
ANS : (-3,2)
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11)
x + y = -4
x - y = 2
2x = -2
x = -1
-1 + y = -4
y = -3
ANS : (-1,-3)
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12)
x + y = 10
y = x + 8
x + (x + 8) = 10
x + x + 8 = 10
2x + 8 = 10
2x = 2
x = 1
y = 1 + 8 = 9
ANS : (1,9)
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13)
3x + y = 5
4x - 7y = -10
3x + y = 5
y = -3x + 5
4x - 7(-3x + 5) = -10
4x + 21x - 35 = -10
25x = 25
x = 1
y = -3(1) + 5 = -3 + 5 = 2
ANS : (1,2)
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14)
y - 2x = -5
3y - x =5
y - 2x = -5
y = 2x - 5
3(2x - 5) - x = 5
6x - 15 - x = 5
5x = 20
x = 4
y = 2(4) - 5 = 8 - 5 = 3
ANS : (4,3)
2007-01-01 15:58:12 · answer #1 · answered by Sherman81 6 · 0⤊ 0⤋
Hint:
3x - y = 10 3x - y = 10
-x + y = -4 = + (-3x + 3y = -12)
2y = -2 y = -1
or y = -4 + x
using substitution for the first first equation
3x - (-4 +x) =10
3x +4 - x =10
2x + 4 =10
2x = 6
x = 3
2007-01-01 11:10:53 · answer #2 · answered by Michael E 2 · 0⤊ 0⤋
This very simple!
Given: 3x - y = 10 and -x + y = -4
take a (3, -7)
Plug x=3 and y=-7 in both of the eq. and see which one works!
If this choice don't work try others.
Other way is to solve the eqs and find x and y!
3x - y = 10.................(1)
(-x + y = -4) X 3
-3x+3y=-12...............(2)
add (1) and (2)
2y=-2
y=-1
so the answer is c!!!!
I hope this helps!!
2007-01-01 11:13:11 · answer #3 · answered by smart-crazy 4 · 0⤊ 0⤋
5x + 2y = 15 -5x - 2y = -5 _____________ 0 = 10 you sparkling up utilizing combining words, you upload both equations. 0=10 potential this device of equation has no answer in any respect, because the slopes of both strains are a similar, in different words are parallel strains, so there is not element of interception
2016-12-01 10:03:18 · answer #4 · answered by Anonymous · 0⤊ 0⤋
I will not do all these but I can easily help you if you e-mail me. Solve for x or y in one of the equations so that x=... or y=... then fill the "..." in for the x or y in the other equation and solve for the other variable and using that answer fill it into one of the original equations then you should have x and y.
2007-01-01 10:58:16 · answer #5 · answered by Dirk D 2 · 0⤊ 0⤋
For shame: posting multiple choice questions...
2007-01-01 10:57:15 · answer #6 · answered by modulo_function 7 · 0⤊ 0⤋