Question

factorise 9(a-2)² - 16(a+2)²​

Answer 1

Answer:

-(7a+2)(a+14)

Step-by-step explanation:

Given Equation is 9(a - 2)2 16(a +2 2

[3(a- 2)12 - [4(a +2)r2

We know that a^2 - b^2 = (a + b){a - b)

[3(a - 2) +4(a + 2)]13(a - 2) - 4(a +2)]

(3a -6+ 4a +8)(3a - 6- 4a- 8)

(7a+ 2)(-a - 14)

-(7a + 2)(a + 14).

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Answer 2

Answer:

a = -14  

a = -2/7

Step-by-step explanation:

9(a - 2)² - 16(a + 2)²​ = 0

{Using identity : (a - b)²​ = a²​ + b²​ - 2ab }

                          (a + b)²​ = a²​ + b²​ + 2ab   ​        

9[a²​ + (2)²​ - 2(a)(2)] - 16[a²​ + (2)² + 2(a)(2)​] = 0

9[a²​ + 4 - 4a] - 16[a²​ + 4 + 4a] = 0

9a²​ + 36 - 36a - 16a²​ - 64 - 64a = 0

-7a²​ - 100a - 28 = 0

7a²​ + 100a + 28 = 0

7a² + 98a + 2a + 28 = 0

7a(a + 14) + 2(a + 14) = 0

(a + 14)(7a + 2) = 0

a + 14 = 0                              7a + 2 = 0

$a=-14$                                7a = -2

                                              $a=\frac{-2}{7}$