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Let’s check out your problem:
Solve using elimination.
\newline
−
7
x
−
8
y
=
−
15
-7x - 8y = -15
−
7
x
−
8
y
=
−
15
\newline
8
x
+
8
y
=
8
8x + 8y = 8
8
x
+
8
y
=
8
\newline
(_____, _____)
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Math Problems
Grade 8
Solve a system of equations using elimination
Full solution
Q.
Solve using elimination.
\newline
−
7
x
−
8
y
=
−
15
-7x - 8y = -15
−
7
x
−
8
y
=
−
15
\newline
8
x
+
8
y
=
8
8x + 8y = 8
8
x
+
8
y
=
8
\newline
(_____, _____)
Write Equations:
Write down the
system of equations
.
\newline
−
7
x
−
8
y
=
−
15
-7x - 8y = -15
−
7
x
−
8
y
=
−
15
\newline
8
x
+
8
y
=
8
8x + 8y = 8
8
x
+
8
y
=
8
Add Equations:
Add the two equations together to eliminate the
y
y
y
variable.
\newline
(
−
7
x
−
8
y
)
+
(
8
x
+
8
y
)
=
(
−
15
)
+
(
8
)
(-7x - 8y) + (8x + 8y) = (-15) + (8)
(
−
7
x
−
8
y
)
+
(
8
x
+
8
y
)
=
(
−
15
)
+
(
8
)
Perform Addition:
Perform the addition.
\newline
−
7
x
+
8
x
=
1
x
-7x + 8x = 1x
−
7
x
+
8
x
=
1
x
\newline
−
8
y
+
8
y
=
0
y
-8y + 8y = 0y
−
8
y
+
8
y
=
0
y
(which cancels out)
\newline
−
15
+
8
=
−
7
-15 + 8 = -7
−
15
+
8
=
−
7
\newline
This simplifies to:
\newline
x
=
−
7
x = -7
x
=
−
7
Solve for
x
x
x
:
Substitute
x
=
−
7
x = -7
x
=
−
7
into one of the original equations to solve for
y
y
y
. We'll use the first equation.
−
7
(
−
7
)
−
8
y
=
−
15
\,-7(-7) - 8y = -15
−
7
(
−
7
)
−
8
y
=
−
15
Substitute
x
x
x
:
Perform the multiplication.
49
−
8
y
=
−
15
49 − 8y = −15
49−8
y
=
−15
Perform Multiplication:
Subtract
49
49
49
from both sides to isolate the term with
y
y
y
.
\newline
49
−
8
y
−
49
=
−
15
−
49
49 - 8y - 49 = -15 - 49
49
−
8
y
−
49
=
−
15
−
49
Isolate y Term:
Simplify the equation.
−
8
y
=
−
64
-8y = -64
−
8
y
=
−
64
Simplify Equation:
Divide both sides by
–
8
–8
–8
to solve for
y
y
y
.
–
8
y
–
8
=
–
64
–
8
\frac{–8y}{–8} = \frac{–64}{–8}
–8
–8
y
=
–8
–64
Divide by
−
8
-8
−
8
:
Calculate the value of
y
y
y
.
y
=
8
y = 8
y
=
8
More problems from Solve a system of equations using elimination
Question
Solve using substitution.
5
x
−
2
y
=
−
7
5x - 2y = -7
5
x
−
2
y
=
−
7
x
=
−
5
x = -5
x
=
−
5
(_,_)
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Posted 5 months ago
Question
Is
(
1
,
1
)
(1,1)
(
1
,
1
)
a solution to this system of equations?
\newline
4
x
+
10
y
=
14
4x + 10y = 14
4
x
+
10
y
=
14
\newline
x
+
6
y
=
7
x + 6y = 7
x
+
6
y
=
7
\newline
Choices:
\newline
(A) yes
\newline
(B) no
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Posted 5 months ago
Question
Which describes the system of equations below?
\newline
y
=
–
3
x
+
9
y = –3x + 9
y
=
–3
x
+
9
\newline
y
=
–
3
x
+
9
y = –3x + 9
y
=
–3
x
+
9
\newline
Choices:
\newline
(A) consistent and independent
\text{(A) consistent and independent}
(A) consistent and independent
\newline
(B) consistent and dependent
\text{(B) consistent and dependent}
(B) consistent and dependent
\newline
(C) inconsistent
\text{(C) inconsistent}
(C) inconsistent
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Posted 5 months ago
Question
Solve using elimination.
\newline
7
x
−
8
y
=
−
17
7x - 8y = -17
7
x
−
8
y
=
−
17
\newline
−
7
x
+
3
y
=
2
-7x + 3y = 2
−
7
x
+
3
y
=
2
\newline
(
_
_
_
_
,
_
_
_
_
)
(\_\_\_\_, \_\_\_\_)
(
____
,
____
)
Get tutor help
Posted 5 months ago
Question
Solve.
\newline
x
=
−
2
x = -2
x
=
−
2
\newline
−
2
x
+
2
y
=
−
8
-2x + 2y = -8
−
2
x
+
2
y
=
−
8
\newline
(
_
_
_
_
,
_
_
_
_
)
(\_\_\_\_, \_\_\_\_)
(
____
,
____
)
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Posted 8 months ago
Question
Write a system of equations to describe the situation below, solve using any method, and fill in the blanks.
\newline
At a community barbecue, Mrs. Wilkerson and Mr. Hogan are buying dinner for their families. Mrs. Wilkerson purchases
3
3
3
hot dog meals and
3
3
3
hamburger meals, paying a total of
$
36
\$36
$36
. Mr. Hogan buys
1
1
1
hot dog meal and
3
3
3
hamburger meals, spending
$
26
\$26
$26
in all. How much do the meals cost?
\newline
Hot dog meals cost
$
\$
$
_______ each, and hamburger meals cost
$
\$
$
________ each.
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Posted 8 months ago
Question
Solve the system of equations by substitution.
\newline
−
3
x
−
y
−
3
z
=
−
11
-3x - y - 3z = -11
−
3
x
−
y
−
3
z
=
−
11
\newline
z
=
5
z = 5
z
=
5
\newline
x
−
y
+
3
z
=
19
x - y + 3z = 19
x
−
y
+
3
z
=
19
\newline
(____.____,____)
Get tutor help
Posted 5 months ago
Question
Solve the system of equations by elimination.
\newline
x
−
3
y
−
2
z
=
10
x - 3y - 2z = 10
x
−
3
y
−
2
z
=
10
\newline
3
x
+
2
y
+
2
z
=
14
3x + 2y + 2z = 14
3
x
+
2
y
+
2
z
=
14
\newline
2
x
−
3
y
−
2
z
=
16
2x - 3y - 2z = 16
2
x
−
3
y
−
2
z
=
16
\newline
(
_
,
_
,
_
)
(\_,\_,\_)
(
_
,
_
,
_
)
Get tutor help
Posted 5 months ago
Question
Solve the system of equations.
\newline
y
=
x
2
+
36
x
+
3
y = x^2 + 36x + 3
y
=
x
2
+
36
x
+
3
\newline
y
=
22
x
−
37
y = 22x - 37
y
=
22
x
−
37
\newline
Write the coordinates in exact form. Simplify all fractions and radicals.
\newline
(
_
,
_
)
(\_,\_)
(
_
,
_
)
\newline
(
_
,
_
)
(\_,\_)
(
_
,
_
)
Get tutor help
Posted 5 months ago
Question
Solve the system of equations.
\newline
y
=
−
x
−
24
y = -x - 24
y
=
−
x
−
24
\newline
x
2
+
y
2
=
488
x^2 + y^2 = 488
x
2
+
y
2
=
488
\newline
Write the coordinates in exact form. Simplify all fractions and radicals.
\newline
(
_
,
_
)
(\_,\_)
(
_
,
_
)
\newline
(
_
,
_
)
(\_,\_)
(
_
,
_
)
Get tutor help
Posted 5 months ago
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