If $ a=2 $ and $ b=3 $, find the value of

1. $ a+b $
2. $ a^{2}+a b $
3. $ 2 a-3 b $
4. $ 5 a^{2}-2 a b $

Given:

\( a=2 \) and \( b=3 \)

To do:

We have to find the value of

(i) \( a+b \)
(ii) \( a^{2}+a b \)
(iii) \( 2 a-3 b \)
(iv) \( 5 a^{2}-2 a b \)

Solution:

(i) $a+b=2+3$

$=5$

(ii) $a^2+ab=(2)^2+2\times3$

$=4+6$

$=10$

(iii) $2a-3b=2(2)-3(3)$

$=4-9$

$=-5$

(iv) $5a^2-2ab=5(2)^2-2(2)(3)$

$=5(4)-12$

$=20-12$

$=8$