Question

the area of a rectangular barnyard is given by the trinomial 6x^2+7x-20

Answer 1

god girl

Answer 2

@GODGIRL

Answer 3

Whats ur answer choices?

Answer 4

@crazyinlove

Answer 5

2x-5 and 3x-4
-2x-5 and -3x-4
2x-5 and 3x-4
2x-5 and 3x-4

Answer 6

kk jus a sec

Answer 7

ok

Answer 8

uhmm sorry but i have no idea on how to figure this out maybe @AccessDenied or @mathmale could help . :) Sorry again! wish i could help :/

Answer 9

thank u for trying

Answer 10

Area for rectangle is base times height. So if we can find two factors of 6x^2+7x-20, those would be our base and height. Did you have any ideas on how to begin factoring it?

Answer 11

no not really

Answer 12

I believe from ax^2 + bx + c, we start by looking for factors of a*c that add up to b.
So a*c = 6*-20. One factor will be negative, and we have to add the two factors to get: b = 7
-120 = 15*-8 <-- these two factors seem to add up to 7, so we rewrite:
6x^2 + 7x - 20 = 6x^2 + (15x - 8x) - 20
= (6x^2 + 15x) + (-8x - 20)
So that we can factor by grouping. Factor each individual group until we get a similar factor in each, then pull that factor out.

Answer 13

The first group we could pull out a 3x. 6x^2 + 15x = 3x (2x + 5).
The second group, we could take out -4: -8x - 20 = -4 (2x + 5)
So that both factors hold a (2x + 5), we pull it out: (2x + 5)(3x - 4)

Answer 14

thats actually what i got but that wasn't a answer choice so i was like........stuck basically

Answer 15

I'm guessing one of the last answer choices is written incorrectly. (They're both the same, one must have a + sign)

Answer 16

Actually, now that I look at it again... the first, third AND fourth are the same. o.o

Answer 17

Yeah so @crazyinlove do any of ur answer choices have (2x+5)(3x-4)

Answer 18

ok thank u

Answer 19

Alternatively, you could work in reverse: just expand out each answer choice and see which one gives you the correct area. That may or may not take more time if you don't remember the factoring method.