How do you solve 1+ 3a = - 8- 4a?

2 Answers
Mar 25, 2018

a=-9/7

Explanation:

"collect terms in a on the left and numeric values on the "
"right side of the equation"

"add 4a to both sides"

1+3a+4a=-8cancel(-4a)cancel(+4a)

rArr1+7a=-8

"subtract 1 from both sides"

cancel(1)cancel(-1)+7a=-8-1

rArr7a=-9

"divide both sides by 7"

(cancel(7) a)/cancel(7)=(-9)/7

rArra=-9/7

color(blue)"As a check"

Substitute this value into the equation and if both sides are equal then it is the solution.

"left "=7/7-27/7=-20/7

"right "=-56/7+36/7=-20/7

rArra=-9/7" is the solution"

Mar 25, 2018

a = -(9)/(7)

Explanation:

1+3a=−8−4a    Solve for a

1) Add 4a to both sides to collect all the a terms on the same side.
After you have added, you get this:
1 + 7a = - 8

2) Subtract 1 from both sides to isolate the 7a term
After you subtract, you will have this:
7a = - 9

3) Divide both sides by 7 to isolate a
a = -(9)/(7) larr answer

color(white)(mmmmmmmm)―――――――――

Check
1) Sub in -(9)/(7) in the place of a in the original equation

1+3a=−8−4a

1+3(-(9)/(7)) "should equal"−8−4(-(9)/(7))

2) Clear the parentheses by distributing the coefficients

1 - (27)/(7)  "should equal" - 8 +(36)/(7)

3) To add, give the whole numbers the common denominator of 7

(7)/(7) - (27)/(7) "should equal" - (56)/(7) +(36)/(7)

4) Add like terms

-(20)/(7)  "does equal" - (20)/(7)

Check