/sci/ - Science & Math

[Anonymous No.1988580]

ok this is probably pathetic but I can't solve this.

My legend says it's supposed to be t= 0.70.

[Anonymous No.1988590]

quadratic equation that bitch

[Anonymous No.1988600]

>quadratic
4.9t^2 + 2.3t - 4 = 0

Have fun.

[Anonymous No.1988601]

>>1988590
I tried that! I keep getting false answers!

I must be missing something or making some steps wrong.

0=-2.3t - 4.9t^2 + 4
is what I've been going by, did I miss something?

[Anonymous No.1988620]

-4 = -2.3t - 4.9t^2
4.9t^2 + 2.3t - 4 = 0

Quadratic equation that bitch.

[Anonymous No.1988624]

>>1988601
Well it's solved for you, just calculate the discriminant, find it's >0 and calculate the 2 solutions t1 and t2

[EK !D96TK2PSsI No.1988632]

you can quadratic it either way, but i tend to fix it so most of the terms are posotive, so have "4.9t^2 + 2.3t - 4 = 0" instead of "-2.3t - 4.9t^2 + 4 = 0"
although both are correct

[Anonymous No.1988664]

I quad it but I don't get tx=0.70 like my coursebook says!

[Anonymous No.1988690]

>newfag having trouble with his homework
>goes to /sci/ and wastes 30 mins of his time
> doesn't get his anwser
>realises he should've paid fucking attention during class

[EK !D96TK2PSsI No.1988692]

ti s 0.699
or -1.17
to 3sf

...so 0.7 is correct OP.
quadratic formula is this, in case you don't know it. where 4.9t^2 + 2.3t - 4 = Ax^2 +Bx +C

[EK !D96TK2PSsI No.1988696]

>>1988664
what did you get?
if you get 0.699 or 0.698, it is close enough to 0.7 for you to round it, and call 0.7 the correct answer.

[Anonymous No.1988695]

>>1988664
Never mind that! I just made a small mistake! I got this!

Thanks guys!

[Anonymous No.1988702]

It's
-4.9t^2 - 2.3t +4 = 0
tx=0.70 v tx=-1.17

[Anonymous No.1988711]

>>1988696
that's what I got, 0.698 something. oh and -1.17 but that can't be cause t>0

[Anonymous No.1988717]

1 more time slowly, cuz you seem to be an idiot:

-4 = -2.3t - 4.9t² I +2.3t I + 4.9t²

-> 4.9t² + 2.3t - 4 = 0

--- Y ... Y -> extract the root of this

t 1/2 = -b +/- (Y b² + 4 x a x c Y) / 2 x a
->
-2.3 +/- (Y 2.3² + 4 x 4.9 x 4 Y) / 2 x 4.9

-2.3 +/- (Y 5.29 + 78.4 Y) / 9.8

-2.3 +/- Y 83.69 Y / 9.8

-2.3 +/- 9.15 / 9.8

t1= (-2.3 + 9.15) / 9.8 = 0.699
t2= (-2.3 - 9.15) / 9.8 = 1.17

[Anonymous No.1988731]

>>1988717
I solved it a couple of posts back but thanks.

[Anonymous No.1988748]

sry, didn´t mean to call you an idiot, came to /sci/ straight from /b/ and i am still being affected by the negative powers of b´s brainfuck, and i´m kinda high.. yes indeed, i´m high :D
when will you guys in the us have the results of prop 19?

[Anonymous No.1988758]

Sigh.

<span class="math"> -4 = -2.3t - 4.9t^2 ||+4
-2.3t - 4.9t^2 + 4 = 0

t=\frac{-b \pm \sqrt {b^2-4ac}}{2a}
t=\frac{-(-2.3) \pm \sqrt {(-2.3)^2-4× (-4.9)×4}}{2×(-4.9}

t_{1} ≈ -1.17
t_{2} ≈ 0.70 [/spoiler]

[Anonymous No.1988762]

Sigh.

<span class="math"> -4 = -2.3t - 4.9t^2 ||+4
-2.3t - 4.9t^2 + 4 = 0

t=\frac{-b \pm \sqrt {b^2-4ac}}{2a}
t=\frac{-(-2.3) \pm \sqrt {(-2.3)^2-4× (-4.9)×4}}{2×(-4.9}

t_{1} ≈ -1.17
t_{2} ≈ 0.70 [/spoiler]

[Anonymous No.1988779]

derp.

<span class="math"> -4 = -2.3t - 4.9t^2 ||+4[/spoiler]
<span class="math">-2.3t - 4.9t^2 + 4 = 08[/spoiler]

<span class="math">t=\frac{-b \pm \sqrt {b^2-4ac}}{2a}[/spoiler]
<span class="math">t=\frac{-(-2.3) \pm \sqrt {(-2.3)^2-4× (-4.9)×4}}{2×(-4.9}[/spoiler]

<span class="math">t_{1} ≈ -1.17[/spoiler]
<span class="math">t_{2} ≈ 0.70 [/spoiler]

[Anonymous No.1988786]

derp.

<span class="math"> -4 = -2.3t - 4.9t^2 ||+4[/spoiler]
<span class="math">-2.3t - 4.9t^2 + 4 = 0[/spoiler]

<span class="math">t=\frac{-b \pm \sqrt {b^2-4ac}}{2a}[/spoiler]
<span class="math">t=\frac{-(-2.3) \pm \sqrt {(-2.3)^2-4× (-4.9)×4}}{2×(-4.9}[/spoiler]

<span class="math">t_{1} ≈ -1.17[/spoiler]
<span class="math">t_{2} ≈ 0.70 [/spoiler]