Posted by **ant** on Friday, June 4, 2010 at 6:32pm.

What number is used to complete the square for the equation x^2 + 5x = 0?

a) 25

b) 6.25

c) 2.5

d) 10

d

- algebra -
**MathMate**, Friday, June 4, 2010 at 7:00pm
(d) is not correct.

When we need to complete the square of an expression, we examine the coefficients of the x² and x terms.

To complete the square of a general quadratic equation

ax²+bx+c

we first rewrite it as:

a(x² + (b/a)x + c/a)

to make the coefficient of x² equal to 1.0 inside the parentheses.

After that, we regroup the terms as

a( (x+(b/2a))² + c/a - (b/2a)² )

Therefore the number to complete the square is b/2 if a=1.

Post if you need further explanations.

## Answer This Question

## Related Questions

- algebra - What number is used to complete the square for the equation x^2 + 5x...
- algebra - what number is used to complete the square for the equation y^2 + 16...
- algebra - What number is used to complete the square for the equation y^2 + 16...
- algebra - What number is used to complete the square for the equation x^2 = 20x...
- Algebra - Which of the following statements is true? A. Any quadratic equation ...
- Pre-Cal - Christian is solving the equation x2 – 12x = 4 by completing the ...
- math,help,algebra I - I need help can someone help me get unstuck and let me ...
- Algebra - The Robertson's find that have used 1/2 gallon of paint to cover 480 ...
- algebra - Replace each equation with constants to complete the square and form a...
- Pre-Algebra - How does finding the square root of a number compared to finding ...

More Related Questions