How do you solve #-2.5x + 1.4y = -10.2# and #1.2x - 4.5y = -21.9#?

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Answer 1 · 2018-04-25T11:58:23

Solution: #x=8,y=7#

# -2.5 x +1.4 y = -10.2 (1) ; 1.2 x -4.5 y = -21.9 (2) #

Multiplying by #10# on both sides of the equations (1) and (2) we

get, # -25 x +14 y = -102 (3) ; 12 x -45 y = -219 (4) #

Multiplying by #12# on both sides of the equation (3) we get,

# -300 x +168 y = -1224 (5 )#

Multiplying by #25# on both sides of the equation (4) we get,

#300 x - 1125 y = -5475 (6) # Adding equations (5) and (6)

we get, #-957 y = -6699 :. y =( -6699)/-957= 7 # Putting

#y=7# in equation (3) we get #-25 x + 14*7 =-102# or

#-25 x =-102-98 or -25 x= -200 or x = (-200)/-25=8#

Solution: #x=8,y=7# [Ans]