Question

a^2 – 5a – 20
factor this trinomial i know how to do it but i cant figure it out , can sombody give me a strategy rather than guesses?

Answer 1

complete the square

Answer 2

Works every time....

Answer 3

explain please?

Answer 4

Formula is good as well...

Answer 5

completing a square is a method where you create a perfect square binomial plus something extra

Answer 6

Im still lost sorry?

Answer 7

take half the "a" term and square it: (5/2)^2

add and subtract this from the original ... your essentially adding zero to it so that the value remains the same and only the form changes

Answer 8

a^2 – 5a = 20
First off, write it like that...

Answer 9

Ok, I will Amistre to it...:-)

Answer 10

if you start out like estudier mentions, you add that value to each side to keep things balanced

Answer 11

so
a^2=20+5a?

Answer 12

you might be better off just using the quadratic formula ...

trying to expalin "completing the square" is abit difficult

Answer 13

can you show me that then ?

Answer 14

given a quadratic of the form:\[fx^2+mx+l\] we can use a formula to calculate the xs\[\frac{-m\pm\sqrt{m^2-4fl}}{2f}\]

Answer 15

i woulda used the abcs, but it mighta confused you since your expression uses a as the variable

Answer 16

can you plug in the numbers for me as an example?

Answer 17

im sure youre capable of figureing out which number is the (f)irst, (m)iddle, and (l)ast to plug in ...

Answer 18

Ok thanks

Answer 19

if you want, i can chk your work to see if you did it correctly

Answer 20

It has no rational zeros ...

Answer 21

Correct solutions are irrational (that's why you can't easily guess at the roots).

Answer 22

soooo...?

Answer 23

The formula has given you the roots, right?