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Pair of Linear Equations in Two Variables
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27/05/2021 12:11 pm
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Solve the following pair of linear equations by the substitution and cross-multiplication methods:
8x + 5y = 9
3x + 2y = 4
1 Answer
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27/05/2021 12:12 pm
8x + 5y = 9 …………………..(1)
3x + 2y = 4 ……………….….(2)
From equation (2) we get
x = (4 – 2y )/ 3 ……………………. (3)
Using this value in equation 1, we get
8(4-2y)/3 + 5y = 9
32 – 16y +15y = 27
-y = -5
y = 5 ……………………………….(4)
Using this value in equation (2), we get
3x + 10 = 4
x = -2
Thus, x = -2 and y = 5.
Now, Using Cross Multiplication method:
8x +5y – 9 = 0
3x + 2y – 4 = 0
x/(-20+18) = y/(-27 + 32 ) = 1/(16-15)
-x/2 = y/5 =1/1
∴ x = -2 and y =5.