2x + 3y = 20 and 2x + y = 4 solve by cross multiplication method
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Answer:
Correct option is
C
(5,7)
3x+4y=43 ----- (1)
−2x+3y=11 ----- (2)
First use formula for cross multiplication method:
b
1
c
2
−b
2
c
1
x
=
c
1
a
2
−a
1
c
2
y
=
a
2
b
2
−a
2
b
1
−1
So, from equation (1) and (2) we can write the value of a, b and c.
4×11−3×43
x
=
43×(−2)−3×11
y
=
3×3−(−2)×4
−1
44−129
x
=
−86−33
y
=
9+8
−1
−85
x
=
−119
y
=
17
−1
−85
x
=
17
−1
x=
17
85
=5
−119
y
=
17
−1
y=
17
119
=7
The solution is (5,7)
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