We are given a system of two linear equations: $4p + 2q = 62$ $8p - q = 59$ We need to determine if the two proposed methods for solving the system are valid. Method 1: Multiply the first equation by 2, then subtract the second equation from the result. Method 2: Multiply the second equation by 2, then add the result to the first equation.

AlgebraSystem of Linear EquationsSolving EquationsLinear Algebra
2025/3/11

1. Problem Description

We are given a system of two linear equations:
4p+2q=624p + 2q = 62
8pq=598p - q = 59
We need to determine if the two proposed methods for solving the system are valid.
Method 1: Multiply the first equation by 2, then subtract the second equation from the result.
Method 2: Multiply the second equation by 2, then add the result to the first equation.

2. Solution Steps

Let's analyze each method.
Method 1:
First equation multiplied by 2:
2(4p+2q)=2(62)2(4p + 2q) = 2(62)
8p+4q=1248p + 4q = 124
Subtracting the second equation from the result:
(8p+4q)(8pq)=12459(8p + 4q) - (8p - q) = 124 - 59
8p+4q8p+q=658p + 4q - 8p + q = 65
5q=655q = 65
q=13q = 13
Substituting q=13q = 13 into the first equation:
4p+2(13)=624p + 2(13) = 62
4p+26=624p + 26 = 62
4p=364p = 36
p=9p = 9
Method 2:
Second equation multiplied by 2:
2(8pq)=2(59)2(8p - q) = 2(59)
16p2q=11816p - 2q = 118
Adding the result to the first equation:
(16p2q)+(4p+2q)=118+62(16p - 2q) + (4p + 2q) = 118 + 62
16p2q+4p+2q=18016p - 2q + 4p + 2q = 180
20p=18020p = 180
p=9p = 9
Substituting p=9p = 9 into the first equation:
4(9)+2q=624(9) + 2q = 62
36+2q=6236 + 2q = 62
2q=262q = 26
q=13q = 13
Both methods yield the same solution for pp and qq.
The original system is:
4p+2q=624p + 2q = 62
8pq=598p - q = 59
Substituting p=9p = 9 and q=13q = 13 into both equations to verify the solution.
4(9)+2(13)=36+26=624(9) + 2(13) = 36 + 26 = 62
8(9)13=7213=598(9) - 13 = 72 - 13 = 59
Thus, both methods are valid.

3. Final Answer

Both strategies work for solving the system. The solution is
p=9p = 9
q=13q = 13

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