Question

solve by quadratic formula (x+3)^2-81​

Answer 1

Answer:

Hence, the values of x = +6 , -12

Explanation :

Given,

P(x) = (x + 3)^2 - 81

Now, we know that,

(a + b)^2 = a^2 + b^2 + 2ab

Then,

=> x^2 + 9 + 6x - 81 = 0

=> x^2 + 6x - 72 = 0

On using the method of splitting the middle term, we get,

=> x^2 + 12x - 6x - 72 = 0

=> x(x + 12) - 6(x + 12) = 0

=> (x - 6)(x + 12) = 0

Here either (x - 6) = 0 or (x + 12) = 0

So for the values of x,

(i) (x - 6) = 0

=> x = +6

(ii) (x + 12) = 0

=> x = -12

Hence, the values of x = +6 , -12