Question

2x + y = 7
5x + y = 9
Solve the system of equations.

Answer 1

do you prefer substitution or elimination ?

Answer 2

Elimination :)

Answer 3

2x + y = 7
5x + y = 9 --->(-1)
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2x + y = 7
-5x - y = -9 (result of multiplying by -1)
------------add
-3x = -2
x = 2/3

now sub 2/3 in for x in either equation to find y
2x + y = 7
2(2/3) + y = 7
4/3 + y = 7
y = 7 - 4/3
y = 21/3 - 4/3
y = 17/3

check..
5x + y = 9
5(2/3) + 17/3 = 9
10/3 + 17/3 = 9
27/3 = 9
9 = 9 (correct)

x = 2/3 and y = 17/3

I always hated the ones with fractions...lol

Answer 4

What if it's a problem like this?
Find the solution to the equations.

2x - y = -3
x + y = 0