the answer of this question is
x= 3/7 and y=2/3
solve the following pairs of equations by cross multiplication method
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Answer:
Step-by-step explanation:
6/x+4/y=20.
9/x-7/y=10.5.
Let x be 1/a and y be 1/b .
Hence 6a+4b=20, i.e, 6a+4b-20=0.(1)
And 9a-7b=10.5 i.e,9a-7b-10.5=0 I.e,18a-14b-31=0.(2) (mutiplied by 2 to remove decimal point).
Using formula for cross multiplication method:
x/b1c2-b2c1= y/c1a2-c2a1= -1/a1b2-b2a1.
Multiplying (1) by 7 and (2) by 4, we get
42a+28b=140 ...(3)
36a−28b=42 ...(4)
Adding (3) and (4),
78a=182
a=
78
182
=
6
14
=
3
7
Substituting a=
3
7
in (1), we get b as
14+4b=20
4b=6
b=
4
6
=
2
3
Now, a=
x
1
, so x=
a
1
=
7
3
b=
y
1
, so y=
b
1
=
3
2
x=
7
3
,y=
3
2
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