How do you solve #7a=3-5b # and #2a+b=0#?

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Answer 1 · 2016-05-09T15:04:29

The solution for the system of equations is:
#color(green)(a = -1 #

#color(green)(b = 2#

#7a = 3 - 5b#..........equation #(1)#

#2a + b = 0#

#color(green)(b = -2a#..............equation #(2)#

Solving by substitution:

Substituting equation #2# in #1#:

#7a = 3 - 5b#

#7a = 3 + (- 5) * color(green)((-2a))#

#7a = 3 + 10a#

#7a - 10a = 3 #

#- 3a = 3 #

#a = 3 / (-3) #

#color(green)(a = -1 #

Finding #b# from equation #2# :

#b = -2a#

#b = -2 * (-1)#

#color(green)(b = 2#