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Question
Solve the system of equations by using the method of cross multiplication:
3x + 2y + 25 = 0, 2x + y + 10 = 0
Solution
The given equations are:
3x + 2y + 25 = 0 …….(i)
2x + y + 10 = 0 …….(ii)
Here `a_1 = 3, b_1 = 2, c_1 = 25, a_2 = 2, b_2 = 1 and c_2 = 10`
By cross multiplication, we have:
\
`∴ x/([2×10 −25 × 1]) = y/([25 × 2 −10 × 3] )= 1/([3 × 1−2 × 2])`
`⇒x/((20−25)) = y/((50−30) )= 1/((3−4))`
`⇒x/((−5)) = y/20 = 1/((−1))`
`⇒x = (−5)/(−1) = 5, y = 20/((−1)) = -20`
Hence, x = 5 and y = -20 is the required solution.
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