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Question 1 of 5
Solve the following systems of equations by substitution.
x-y=8x−y=8
2x+y=12x+y=1
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Substitution Method
- 1)1) make one variable the subject
- 2)2) substitute into second equation
- 3)3) solve the second equation
- 4)4) substitute back
First, label the two equations 11 and 22 respectively.
x-yx−y |
== |
88 |
Equation 11 |
2x+y2x+y |
== |
11 |
Equation 22 |
Next, solve for xx in Equation 11.
x-yx−y |
== |
88 |
x-yx−y+y+y |
== |
88+y+y |
Add yy to both sides |
xx |
== |
8+y8+y |
Simplify |
Substitute xx into Equation 22.
22xx+y+y |
== |
11 |
Equation 22 |
22(8+y)(8+y)+y+y |
== |
11 |
x=8+yx=8+y |
16+2y+y16+2y+y |
== |
11 |
Distribute 22 inside the parenthesis |
16+3y16+3y |
== |
11 |
Simplify |
16+3y16+3y-16−16 |
== |
11-16−16 |
Solve for yy |
3y3y |
== |
-15−15 |
yy |
== |
-5−5 |
Divide both sides by 33 |
Now, substitute the value of yy into Equation 11
x-x−yy |
== |
88 |
Equation 11 |
x-x−(-5)(−5) |
== |
88 |
y=-5y=−5 |
x+5x+5 |
== |
88 |
x+5x+5-5−5 |
== |
88-5−5 |
Simplify |
xx |
== |
33 |
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Question 2 of 5
Solve the following systems of equations by substitution.
2a+b=52a+b=5
5a-3b=75a−3b=7
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The substitution method removes one of the variables by replacement in a pair of systems of equations.
First, label the two equations 11 and 22 respectively.
2a+b2a+b |
== |
55 |
Equation 11 |
5a-3b5a−3b |
== |
77 |
Equation 22 |
Next, solve for bb in Equation 11.
2a+b2a+b |
== |
55 |
2a+b2a+b-2a−2a |
== |
55-2a−2a |
Subtract 2a2a from both sides |
bb |
== |
5-2a5−2a |
Simplify |
Substitute bb into Equation 22.
5a-35a−3bb |
== |
77 |
Equation 22 |
5a-35a−3(5-2a)(5−2a) |
== |
77 |
b=5-2ab=5−2a |
5a-15+6a5a−15+6a |
== |
77 |
Distribute -3−3 inside the parenthesis |
11a-1511a−15 |
== |
77 |
Simplify |
11a-1511a−15+15+15 |
== |
77+15+15 |
Solve for aa |
11a11a |
== |
2222 |
aa |
== |
22 |
Divide both sides by 1111 |
Now, substitute the value of aa into Equation 11
22aa+b+b |
== |
55 |
Equation 11 |
22(2)(2)+b+b |
== |
55 |
a=2a=2 |
4+b4+b |
== |
55 |
4+b4+b-4−4 |
== |
55-4−4 |
Simplify |
bb |
== |
11 |
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Question 3 of 5
Solve the following systems of equations by substitution.
x-y=1x−y=1
2x+y=112x+y=11
Incorrect
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Substitution Method
- 1)1) make one variable the subject
- 2)2) substitute into second equation
- 3)3) solve the second equation
- 4)4) substitute back
First, label the two equations 11 and 22 respectively.
x-yx−y |
== |
11 |
Equation 11 |
2x+y2x+y |
== |
1111 |
Equation 22 |
Next, solve for xx in Equation 11.
x-yx−y |
== |
11 |
x-yx−y +y+y |
== |
11 +y+y |
Add yy to both sides |
xx |
== |
1+y1+y |
Simplify |
Substitute xx into Equation 22.
22xx+y+y |
== |
1111 |
Equation 22 |
22(1+y)(1+y)+y+y |
== |
1111 |
x=1+yx=1+y |
2y+2+y2y+2+y |
== |
1111 |
Distribute 22 inside the parenthesis |
3y+23y+2 |
== |
1111 |
Simplify |
3y+23y+2 -2−2 |
== |
1111 -2−2 |
Solve for yy |
3y3y |
== |
99 |
3y3y ÷3÷3 |
== |
99 ÷3÷3 |
Divide both sides by 33 |
yy |
== |
33 |
Now, substitute the value of yy into Equation 11
x-x−yy |
== |
11 |
Equation 11 |
x-x−(3)(3) |
== |
11 |
y=3y=3 |
x-3x−3 +3+3 |
== |
11 +3+3 |
Add 33 to both sides |
xx |
== |
44 |
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Question 4 of 5
Solve the following systems of equations by substitution.
a-3b=2a−3b=2
2a-b=142a−b=14
Incorrect
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Substitution Method
- 1)1) make one variable the subject
- 2)2) substitute into second equation
- 3)3) solve the second equation
- 4)4) substitute back
First, label the two equations 11 and 22 respectively.
a-3ba−3b |
== |
22 |
Equation 11 |
2a-b2a−b |
== |
1414 |
Equation 22 |
Next, solve for aa in Equation 11.
a-3ba−3b |
== |
22 |
a-3ba−3b +3b+3b |
== |
22 +3b+3b |
Add 3b3b to both sides |
aa |
== |
2+3b2+3b |
Simplify |
Substitute aa into Equation 22.
22aa -b−b |
== |
1414 |
Equation 22 |
22(2+3b)(2+3b) -b−b |
== |
1414 |
a=2+3ba=2+3b |
4+6b-b4+6b−b |
== |
1414 |
Distribute 22 inside the parenthesis |
5b+45b+4 |
== |
1414 |
Simplify |
5b+45b+4 -4−4 |
== |
1414 -4−4 |
Solve for bb |
5b5b |
== |
1010 |
5b5b ÷5÷5 |
== |
1010 ÷5÷5 |
Divide both sides by 55 |
bb |
== |
22 |
Now, substitute the value of bb into Equation 11
a-3a−3bb |
== |
22 |
Equation 11 |
a-3a−3(2)(2) |
== |
22 |
b=2b=2 |
a-6a−6 +6+6 |
== |
22 +6+6 |
Add 66 to both sides |
aa |
== |
88 |
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Question 5 of 5
Solve the following systems of equations by substitution.
2x+5y=72x+5y=7
x-y=7x−y=7
Incorrect
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Progress: 0%
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Substitution Method
- 1)1) make one variable the subject
- 2)2) substitute into second equation
- 3)3) solve the second equation
- 4)4) substitute back
Substitution Method
- 1)1) make one variable the subject
- 2)2) substitute into second equation
- 3)3) solve the second equation
- 4)4) substitute back
First, label the two equations 11 and 22 respectively.
2x+5y2x+5y |
== |
77 |
Equation 11 |
x-yx−y |
== |
77 |
Equation 22 |
Next, solve for xx in Equation 22.
x-yx−y |
== |
77 |
x-yx−y +y+y |
== |
77 +y+y |
Add yy from both sides |
xx |
== |
7+y7+y |
Simplify |
Substitute xx into Equation 11.
22xx +5y+5y |
== |
77 |
Equation 1 |
2(7+y) +5y |
= |
7 |
x=7+y |
14+2y+5y |
= |
7 |
Distribute 2 inside the parenthesis |
14+7y |
= |
7 |
Simplify |
14+7y -14 |
= |
7 -14 |
Solve for y |
7y |
= |
-7 |
7y ÷7 |
= |
-7 ÷7 |
Divide both sides by 7 |
y |
= |
-1 |
Now, substitute the value of y into Equation 2
x- y |
= |
7 |
Equation 2 |
x- (-1) |
= |
7 |
y=-2 |
x+1 |
= |
7 |
Simplify |
x+1 -1 |
= |
7 -1 |
Subtract 1 from both sides |
x |
= |
6 |