Question

Solve using suitable identity.
(a) (5m + 8n)^2
(b) (3x - 1/3x)^2​

Answer 1

Answer:

(a) (5m + 8n)^2 ----> USE (a+b)^2

(b) (3x - 1/3x)^2​ ----> USE (a-b)^2

Answer 2

(a) (5m + 8n)²

⁣ ⁣ ⁣  ⁣ ⁣ By using identity (a+b)²=a²+b²+2ab

→(5m)²+(8n)²+2×5m+8n

→25m²+64n²+80mn

(b) (3x - 1/3x)²

⁣ ⁣ ⁣ ⁣ ⁣ ⁣ By using identity (a-b)²=a²+b²-2ab

→(3x)²+(1/3x)²-2×(3x×(1/3x))

→9x²+1/9x²-2

$\\ \\ \sf \: For \: more \: information$

$\sf(a + b)^{2} = {a}^{2} + {b}^{2} + 2ab$

$\sf(a - b)^{2} = {a}^{2} + {b}^{2} - 2ab$

$\sf(a + b)(a - b) = {a}^{2} - {b}^{2}$

$\sf(a + b + c)^{2} = {a}^{2} + {b}^{2} + {c}^{2} 2ab + 2bc + 2ca$