SOLUTION: I actually have five questions. 1.) What number should be added to the expression x2 + 4x to change it into a perfect square trinomial? 2.) What number should be added

Question 194618: I actually have five questions.

1.) What number should be added to the expression x2 + 4x to change it into a perfect square trinomial?

2.) What number should be added to the expression x2 + 12x to change it into a perfect square trinomial?

3.)Solve the following equation by transforming it into a perfect square trinomial.
x2 - 14x = 15

4.)Solve the following equation by transforming it into a perfect square trinomial.
3x2 + 18x = 21

5.) Solve the following equation by transforming it into a perfect square trinomial.
x2 - 2x = 3

Answer by Mathtut(3670) (Show Source): You can put this solution on YOUR website!
.) What number should be added to the expression x2 + 4x to change it into a perfect square trinomial?
:
take 1/2 of the coefficient of the x term and square it
:
1/2(4)=2 and 2 squared equals 4

2.) What number should be added to the expression x2 + 12x to change it into a perfect square trinomial? 1/2 of 12 =6 and 6 squared is 36
:

:
3.)Solve the following equation by transforming it into a perfect square trinomial.
x2 - 14x = 15
1/2(14)=7 and 7 squared is 49....so if we add 49 inside the parenthesis then we mus subtract 49 outside the parenthesis to keep equation equivilet
:

4.)Solve the following equation by transforming it into a perfect square trinomial.
3x2 + 18x = 21
:
1/2(6)=3 and 3 squared is 9
:
.....notice that instead of creating just 9 we have to multiply this by the 3 outside the parathesis 3(9)=27 so we had to subtract 27 to keep equation equivilent
:

5) Solve the following equation by transforming it into a perfect square trinomial.
x2 - 2x = 3
:
take 1/2(2)=1 and 1 squared is 1
:

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