he simultaneous equations5x + y = 21x - 3y = 9 With working out
Mathematics · Middle School · Thu Feb 04 2021
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Givent he equation:
5x + y = 0
21x - 3y = 9
Determine the value of x and y.
Solution:
Solve first for the value of x in the first equation. To do so transpose 5x to the other side of the equation, hence it must be taken to note that in transposing a number, the sign changes.
5x + y = 0
y = -5x
Substitute the value of y from the first equation to the value of y, of the second equation then solve for x.
21x - 3(-5x) = 9
21x + 15x = 9
36x = 9
Divide both sides by 36 in order to determine the value of x.
36x/36 = 9/36
x = ¼
Substitute the value of x to the formula for y, then solve for y.
y = -5(¼)
y = -5/4
Final answer:
x = ¼
y = -5/4