Find the value of k so that the line through the given points has the given slope. (-4,2k) and (k, -5); m=-1. PLEASE HELP SO STUCK THANKS

Question

kirbykirby · Answer

From the slope formula: $\dfrac{y_2-y_1}{x_2-x_1}$

$$slope =m= \frac{-5-2k}{k-(-4)}=-1 $$

kirbykirby · Answer

Are you able to solve this type of problem now?

anonymous · Answer

I am still comfused :)

kirbykirby · Answer

Do you understand how I applied the slope formula to your problem?

anonymous · Answer

yes

anonymous · Answer

but what do we do after

anonymous · Answer

now do we combind

kirbykirby · Answer

Well you can just solve this like a regular algebra problem. 
$$\frac{-5-2k}{k-(-4)}=-1\
~ \\frac{-5-2k}{k+4}=-1$$
Now cross multiply:
$$ -5-2k=-1(k+4)\
-5-2k=-k=4$$
Are you able to solve for k?

anonymous · Answer

i do not know what you did after -5-2k/k+4=-1. This is the first time learning this.

anonymous · Answer

cross multiply, but how?

kirbykirby · Answer

oh if you have a rational equation like...
$$ \frac{x+1}{3}=\frac{x+2}{x}$$ then what you can do is cross-multiply. That is, the denominator of the 1st fraction multiplies the numerator of the 2nd fraction.
And, the denominator of the 2nd fraction multiplies the numerator of the 1st fraction. 

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