Question

Expand (2a + 5b)² using the identity (a+b)². ​

Answer 1

Answer:

Step-by-step explanation:

using identities

(a-b)²= (a)²-2ab+(b)²

(2a-5b)² =(2a)²-2×2a×5b +(5b)²

4a²-20ab+25b²

Hope it helps to you

Answer 2

To expand : $(2a + 5b )^{2}$ using identity $(a + b )^{2}$ .

Solution :

• According to question we have to expand  $(2a + 5b )^{2}$ using identity $(a + b )^{2}$ .  
• We know that $(a + b)^{2} = a^{2} + 2ab + b^{2}$

• To expand $(2a + 5b )^{2}$  we apply above identity .
• Here , $a = 2a$ and $b = 5b$
• Substituting the values in above identity we get ,

• $(2a + 5b )^{2}$  $= (2a )^{2} + 2 (2a )(5b) +(5b )^{2}$  

                         $= 4a^{2} + 20 ab + 25b^{2}$

Hence , on expanding $(2a + 5b )^{2}$  we get $4a^{2} + 20 ab + 25b^{2}$  .