# Thread: solve the formula for t1

1. ## solve the formula for t1

$
\frac {a} = \frac {-v2-v1}{t2-t1}$

2. it should read a = then that v2-v1 over t2-t1

3. Originally Posted by imbadatmath
$
\frac {a} = \frac {-v2-v1}{t2-t1}$
$a=\frac{v_2-v_1}{t_2-t_1}$

We start by multiplying both sides by $t_2-t_1$

$a(t_2-t_1)=v_2-v_1 \iff at_2-at_1=v_2-v_1$ distribute

$-at_1=v_2-v_1-at_2 \iff t_1=\frac{at_2+v_1-v_1}{a}$ isolate $t_1$

4. Originally Posted by imbadatmath
$
\frac {a} = \frac {-v2-v1}{t2-t1}$
$a(t_2 - t_1) = v_2 - v_1$

$at_2 - at_1 = v_2 - v_1$

$-at_1 = v_2 - v_1 - at_2$

$t_1 = -\frac{v_2 - v_1}{a} - t_2$

By the way, your code reads
\frac {a} = \frac {v2-v1}{t2-t1}

What you wanted was
a = \frac {v2-v1}{t2-t1}

-Dan