Question

What number should be added to the expression x2 + 2x to change it into a perfect square trinomial?









A.

1








B.

2








C.

3








D.

4

Answer 1

Just complete the square if you want to find the last term that makes it a PST.
ax^2 + bx + c = 0
x^2 + 4x
Complete the square: take the "b" term and divide it by 2, then square that number and that will become your "c".
x^2 + 4x + 4 (b = 4, 4/2 is 2 and 2^2 is 4). So your answer is 4.

Answer 2

x^2+2x+1=(x+1)^2; so 1 should be added ;

(x+a)^2=x^2+2ax+a^2 and compare coefficients

Answer 3

Is @ikatouni correct?

Answer 4

no i think he took the wrong question