Question

Select options below
For the system:
2
13
x
+
3
7
y
=
6

4
39
x
−
1
14
y
=
−
1
Multiply the first equation by
Choose
13
20
77
91
and the second by
Choose...
273
546
1092
to clear the denominators using the least common denominator (LCD). The variable
Choose...
x
y
is the better choice to eliminate first.

Answer 1

Multiply the first equation by 91 and the second by 546. The better variable to eliminate first is y.

Reason:
- LCD(13,7)=91, so 91*(2/13 x + 3/7 y = 6) → 14x + 39y = 546.
- LCD(39,14)=546, so 546*(4/39 x − 1/14 y = −1) → 56x − 39y = −546.

The y-terms are 39y and −39y, so adding the equations eliminates y.