197k views
3 votes
Why is the answer A? Plzzz explain.

Why is the answer A? Plzzz explain.-example-1
User Hubcaps
by
8.0k points

1 Answer

3 votes

Answer:


Explanation:

f(x) = x^2 + 4x + 4

f(x + a) = (x + a)^2 + 4(x + a) + 4

f(x + a) = x^2 + 2ax + a^2 + 4x + 4a + 4 Now combine like terms and use the distributive property.

f(x + a) = x^2 + (2a + 4)x + a^2 + 4a + 4

We are told that f(x + a) = x^2 - 6x + 9

So that means that

2a + 4 = - 6 Subtract 4 from both sides.

2a = - 6 - 4

2a = - 10 Divide by 2

a = - 10/2

a = - 5.

But you are not finished. You have to check the last part.

a^2 + 4x + 4 = 9

(a + 2)^2 = 9

Take the square root of both sides

sqrt(a+ 2)^2 = +/- 3

a+2 = 3

a = 1.

Does this work or is it extraneous? It is extraneous because it will not work for 2(a) + 4 = - 6

You get 6 = - 6 which is not correct. But you did give the second best answer.

a + 2 = - 3

a = - 3 - 2

a = - 5 which agrees with your previous answer.

===========

This is an extremely hard or tricky or sneaky problem. It takes a lot of conniving to get the right answer and 1 is not a left field answer. It just does not happen to be correct.

User Nevin Raj Victor
by
8.4k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories