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Solve the simultaneous equations 5x + y = 21 x – 3y = 9 x = ________ y = ________
Question
Solve the simultaneous equations
5x + y = 21
x – 3y = 9
x = ________
y = ________
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Mathematics
3 years
2021-09-02T07:18:55+00:00
2021-09-02T07:18:55+00:00 2 Answers
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Answer:
5x+y=21……equation 1
x-3y=9……equation 2
from1:y=21-5x…..equation 3
substitute y by 21-5x in equation 2
x-3(21-5x)=9
x-63+15x=9
x+15x=9+63
16x=72(we divide both sides by 16)
16÷16=72÷16
therefore x=9/2 or x=4,5
substitute x by 4,5 or 9/2 in equation 3
y=21-5(9/2) or y=21-5(4,5)
y=-3/2 or y=-3/2
prove
5(9/2)-3/2=21
-3/2-3(9/2)=9
Answer:
x=9/2
y= -3/2
Step-by-step explanation:
espero que te sirva:)