doing math at university.. i think its pretty basic im just a retard. question says:
If the line passing through the points (1,a) and (4,-2) is parallel to te line passing through (2,8) and (-7,a+4), what is the valu of a?

So i use M=(y2-y1)/(x2-x1)
for each line and then like substitute them becuase m is equal if they are parallel...
giving me this:

-2-a/4-1 = (a+4)-8 / -7-2

and i looked in the answers.. a=5
????? how?

thanks
Math? No.

Crystal Meth? **** YEAH!
RULE BRITANNIA
the answer is wrong, it should be -5

(-2-a)/3 = a-4/-9
19+9a = 3a-12
6a = -30
a = -5
hmmm, i got minus 5
Quote by magic medicine
the answer is wrong, it should be -5

(-2-a)/3 = a-4/-9
19+9a = 3a-12
6a = -30
a = -5

This is what i got too.....
magic where did the 8 go? you went from (a+4)-8 to a-4 ??
thanks
I got -5 too
Quote by cloudconnects
magic where did the 8 go? you went from (a+4)-8 to a-4 ??
thanks

4-8=-4
may i suggest to any mod veiwing this thread that the 'Only Maths Thread' get stickied?
Quote by cloudconnects
magic where did the 8 go? you went from (a+4)-8 to a-4 ??
thanks

order of operations, a+4 -8 is a-4, you can drop parentheses if its just addition and subtraction, nothing to distribute.
Quote by cloudconnects
magic where did the 8 go? you went from (a+4)-8 to a-4 ??
thanks

I used my uber math skillz to infer that 4-8 = -4
You're doing math in university and you can't do that? 0.o
I'm pretty sure the answer is -5
okay thanks everyone... we have proved... i should not be in university lol.. and that its -5