3. find y if the line through A(-1,2) and B(3,5) is parallel to the line through (0,-1) and (6,y)

Question

anonymous · Answer

Help!!!

anonymous · Answer

find gradient of AB then equate it to gradient of the other line (0.-1) and (6,y)

phi · Answer

what is the slope  (change in Y divided by change in X)  between
 A(-1,2) and B(3,5)  ?

anonymous · Answer

Parellel, means the "gradient" of both the slopes are equal.

FInd the gradient of  line AB 

$$\frac{y_{2}-y_{1}}{x_{2}-x_{1}} = m$$

equate m into 
$$\frac{y-(-1)}{6-0} = m$$

SOlve it u get Y

anonymous · Answer

is y=3/4???

phi · Answer

what did you get for the slope between A and B ?

anonymous · Answer

3/4 is the gradient

anonymous · Answer

to find it substitute gradient for the the second slope

anonymous · Answer

sory, my mistake,  the slope is 3/4

anonymous · Answer

should i cross multiply??

anonymous · Answer

yes u have to

phi · Answer

you could cross multiply, but I would just multiply both sides by 6

anonymous · Answer

why 6???

anonymous · Answer

$$y-(-1) = 6m$$

anonymous · Answer

where is that equation from??

phi · Answer

the 2nd equation, posted by thus,  is the slope of the 2nd line

anonymous · Answer

Do you know the equation to find the gradient of the slope, when the coordinates of 2 points are given?

anonymous · Answer

shi*,,   i think i'm just gonna cross multiply them. xD

anonymous · Answer

so what did u get for Y?

anonymous · Answer

UHM..  -22/4

anonymous · Answer

i think u got your mathematics wrong.

$$y-(-1) = 6m.....   m = 3/4$$
$$y + 1 = 6\times \frac{3}{4}$$
$$y = \frac{9}{2} - 1$$
$$y = \frac{7}{2}$$