Posted by **jasmine20** on Sunday, April 15, 2007 at 4:46pm.

how do i find the following:

is there a formula for this?

Problem #15

Find the constant term that should be added to make the following expression a perfect square trinomial.

x^2+7x

square a few binomials and see if you can see a pattern

e.g. (x+3)^2 = x^2 + 6x + 9

(x-7)^2 = x^2 - 14x + 49

notice the coefficient of the middle term is twice the square root of the last term

so you have to reverse the pattern

take 1/2 of the middle term number, then square it.

for your e.g.

x^2 + 7x + ???

1/2 of 7 is 7/2, which when squared is 49/4

so

x^2 + 7x

=x^2 + 7x + 49/4 - 49/4

=(x+7/2)^2 - 49/4

I added and subtracted the same number to maintain the "equality"

I assume you are learning the method of completing the square.

i am lost?

## Answer this Question

## Related Questions

- Math - Find the constant term that should be added to make the following ...
- math,correction - is this correct Find the constant term that should be added to...
- math,help - Is this trinomial a perfect square x^2-6x+9 if the trinomial starts ...
- MATH - which following trinomial is a perfect square? A. x^2 + 2x - 3 B. x^2 - ...
- Math - this question does not make sense to me. Add the proper constant to the ...
- Algebra 2 - Replace each of the question marks with a value that will make the ...
- Algebra - x^2+7x Which constant should be added to make this expression a ...
- Algebra 2 - Find the value of c that makes the expression a perfect square ...
- Alg 1 - Completing the square: Find the value of c such that each expression is ...
- Algebra 1 - 1. What is the excluded value for the rational expression x^2 - 4/3x...