Here are the solutions to the problems:
1. Solve the system of the simultaneous equations
-
i.
Given the system:
{3x−y=1x−y=−3(1)(2)
Step 1: Subtract equation (2) from equation (1) to eliminate y.
(3x−y)−(x−y)=1−(−3)
3x−y−x+y=1+3
2x=4
Step 2: Solve for x.
x=24
x=2
Step 3: Substitute x=2 into equation (2) to find y.
2−y=−3
−y=−3−2
−y=−5
y=5
The solution is x=2,y=5.
-
ii.
Given the system:
{3x−4y=0x−y=2(1)(2)
Step 1: From equation (2), express x in terms of y.
x=y+2
Step 2: Substitute this expression for x into equation (1).
3(y+2)−4y=0
3y+6−4y=0
−y+6=0
−y=−6
y=6
Step 3: Substitute y=6 back into the expression for x.
x=6+2
x=8
The solution is x=8,y=6.
-
iii.
Given the system:
{x=4−23y−3x+y=−1(1)(2)
Step 1: Substitute the expression for x from equation (1) into equation (2).
−3(4−23y)+y=−1
−12+29y+y=−1
Step 2: Combine the y terms.
−12+29y+22y=−1
−12+211y=−1
Step 3: Add 12 to both sides.
211y=−1+12
211y=11
Step 4: Multiply by 112 to solve for y.
y=11×112
y=2
Step 5: Substitute y=2 back into equation (1) to find x.
x=4−23(2)
x=4−3
x=1
The solution is x=1,y=2.
2. Solve the inequalities
-
i.
31x−21(x−3)<1
Step 1: Distribute 21.
31x−21x+23<1
Step 2: Find a common denominator for the x terms (LCM of 3 and 2 is 6).
62x−63x+23<1
−61x+23<1
Step 3: Subtract 23 from both sides.
−61x<1−23
−61x<22−23
−61x<−21
Step 4: Multiply both sides by -6 and reverse the inequality sign.
x>(−21)×(−6)
x>3
The solution is x>3.
-
ii.
2x+2x+4≤1
Step 1: Subtract 1 from both sides.
2x+2x+4−1≤0
Step 2: Find a common denominator.
2x+2x+4−2x+22x+2≤0
2x+2x+4−(2x+2)≤0
2x+2x+4−2x−2≤0
2x+2−x+2≤0
Step 3: Find critical points by setting the numerator and denominator to zero.
Numerator: −x+2=0⟹x=2
Denominator: 2x+2=0⟹2x=−2⟹x=−1
Step 4: Test intervals (−∞,−1), (−1,2], and [2,∞).
- For x<−1 (e.g., x=−2): 2(−2)+2−(−2)+2=−24=−2≤0. This interval is part of the solution.
- For −1<x≤2 (e.g., x=0): 2(0)+2−0+2=22=1≤0. This interval is not part of the solution.
- For x>2 (e.g., x=3): 2(3)+2−3+2=8−1≤0. This interval is part of the solution.
Note that x=−1 is excluded because it makes the denominator zero. x=2 is included because the inequality is ≤.
The solution is x<−1orx≥2.
-
iii.
54x≤57+52x
Step 1: Subtract 52x from both sides.
54x−52x≤57
52x≤57
Step 2: Multiply both sides by 25.
x≤57×25
x≤27
The solution is x≤27.
-
iv.
21(5x−4≥x−211)
Step 1: Multiply both sides by 2 to clear the fraction.
5x−4≥2(x−211)
5x−4≥2x−11
Step 2: Subtract 2x from both sides.
5x−2x−4≥−11
3x−4≥−11
Step 3: Add 4 to both sides.
3x≥−11+4
3x≥−7
Step 4: Divide by 3.
x≥−37
The solution is x≥−37.
-
v.
5x−2≤3x+6
Step 1: Subtract 3x from both sides.
5x−3x−2≤6
2x−2≤6
Step 2: Add 2 to both sides.
2x≤6+2
2x≤8
Step 3: Divide by 2.
x≤4
The solution is x≤4.
-
vi.
x−7≥−5
Step 1: Add 7 to both sides.
x≥−5+7
x≥2
The solution is x≥2.
3. Solve for x
-
i.
x−23−x+14=0
Step 1: Add x+14 to both sides.
x−23=x+14
Step 2: Cross-multiply.
3(x+1)=4(x−2)
3x+3=4x−8
Step 3: Subtract 3x from both sides.
3=4x−3x−8
3=x−8
Step 4: Add 8 to both sides.
3+8=x
x=11
Check for restrictions: x=2 and x=−1. Our solution x=11 is valid.
The solution is x=11.
-
ii.
93x−5+2x=31
Step 1: Find a common denominator for all terms (LCM of 9 and 3 is 9).
93x−5+918x=93
Step 2: Multiply the entire equation by 9.
3x−5+18x=3
Step 3: Combine like terms.
21x−5=3
Step 4: Add 5 to both sides.
21x=3+5
21x=8
Step 5: Divide by 21.
x=218
The solution is x=218.
-
iii.
7x−5x=710
Step 1: Find a common denominator for the x terms (LCM of 7 and 5 is 35).
355x−357x=710