Any help would be appriciated!

[truemajority]

The directions for this are to factor. I cannot come up with the correct answer, because there are no factors of 15 that will equal -17. Is there something I am doing wrong?

4x2 - 17x + 15

(2x + ?) (2x + ?)

Factors of 15 (1, 15) (-1,-15) (3,5) (-3,-5)

The other problem I ran into was:

The area of a triangle is 35 cm2. The height  is 3

Comments

[tarzanic]

For the first one, try (4x + ?)(x + ?) and your list of factors. One of them will work, but you might need to try each option and FOIL them out. Have you been taught a method for factoring when the coefficient for the x2 is not 1? There is a box method, but I do not know how widely it is taught.

For the second one, you'll first need to get it in the form kb2 + mb + n = 0 where k, m, and n are numbers. You can start by using the distributive property.

[truemajority]

i do not know that method. I will try this though

[tarzanic]

Here is a tutorial for the box method. It can take a bit of practice, but once you master it, it works really well.

[truemajority]

but, with 4x, I would have 4x x 4x, which would give me 16x^2 which wouldn't work.

Could I do 4(x+?)(x+?)

[felixdiecat]

For the first one, I'd attempt the Quadratic Formula and see what it gives you. It might give you a weird number, which would explain a lot... xD

Also:

1/2 b(b-3) = 35

1/2 (b^2-3b) = 35 (assuming that 1/2 is being multiplied by (b(b-3)))

b^2 - 3b = 70

b^2 - 3b - 70 = 0

(b - 10)(b + 7) = 0

b=10, b=-7

:) I think, eh? :)

[felixdiecat]

I think I might've screwed that up. I can't think anymore. xD

[truemajority]

it's ok. It's helpful nonetheless!

[felixdiecat]

Lol. It does work though. The triangle's base and height are 7 and 10. =D

[korean_guy_01]

a) 4 & 1 are also factors of 4.

b) Move the half, distribute, subtract

[just_you_wait]

For Ax^2+Bx+C, you need factors of A*C that add to B, so you want factors of 60 that add to -17, i.e. -12 and -5.

Then 4x^2 -12x -5x +15 becomes 4x(x-3) -5(x-3)=(4x-5)(x-3).