How do solve the following linear system?: # x+2y=1 , 9 x+ 16y =3 #?

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Answer 1 · 2016-02-09T06:41:04

#x=-5# and #y=3#

Let #x+2y=1# the 1st equation
Let #9x+16y=3# the 2nd equation

Use 1st into the 2nd equation

from 1st:
#x=1-2y#

using 2nd:
#9x+16y=3#

#9(1-2y)+16y=3#

#9-18y+16y=3#

#-2y=-6#

#(cancel(-2)y)/cancel(-2)=(-6)/-2#

and #y=3#

Go back to the 1st equation and use #y=3#

#x=1-2y#
#x=1-2*3#
#x=1-6#
#x=-5#

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