How do you solve 3a+b=4 and a-2b=6 using substitution?
1 Answer
Mar 3, 2018
Explanation:
3a+b=4to(1)
a-2b=6to(2)
"from equation "(2)" we obtain "a=6+2bto(3)
color(blue)"substitute "a=6+2b" into equation "(1)
rArr3(6+2b)+b=4
rArr18+6b+b=4
rArr18+7b=4
"subtract 18 from both sides"
cancel(18)cancel(-18)+7b=4-18
rArr7b=-14
"divide both sides by 7"
(cancel(7) b)/cancel(7)=(-14)/7
rArrb=-2
color(blue)"substitute "b=-2" in equation "(1)
3a-2=4
rArr3a=4+2=6
rArra=6/3=2
"the solution is "a=2,b=-2
