Question

Find the value of a and b using substitution method:
$a+b=3$ and $-3a+2b=1$

• A. 1 and 2
• B. 2 and 1
• C. -2 and -1
• D. 2 and -1

Answer 1

The correct option is A 1 and 2

$a+b=3$ ------- (1)
$-3a+2b=1$ ------ (2)
From equation 1:
$a=3-b$
Substitute the value of a in equation 2 :
$-3a+2b=1$
$-3(3-b)+2b=1$
$-9+3b+2b=1$
$5b=10$
$b=\frac{10}{5}=2$
Now, Substitute $b=2$ in equation 1:
$a+b=3$
$a+2=3$
$a=3-2$
$a=1$
Therefore the solution is: $a=1$ and $b=2$