Need help with 1 Math Question

[hasanahmad]

the question is in the image. i need to understand how to solve this 1 question, thanks

[tahaqureshi]

Just let a = 7 and b = 5. (any random numbers will do.)

do this for some other numbers as well, and eventually, the same result will keep popping up all the time. Also, if you do this, the general formula/rule may occur ot you, and you can state that as well.

[hasanahmad]

Originally Posted by tahaqureshi Just let a = 7 and b = 5. (any random numbers will do.) do this for some other numbers as well, and eventually, the same result will keep popping up all the time. Also, if you do this, the general formula/rule may occur ot you, and you can state that as well.

could you explain that

[Amir_rulez]

its simple Hasan.
Take a look:

[tahaqureshi]

ok, take 2 numbers. lets say 7 and 5. and write down two co-ordinates, (5,7) and (7,5).

find the gradient using the formula = (y1 - y2)/(x1 - x2)

the gradient you get should be equal to -1 since the gradeint of y=x is 1.

do this for several pairs of numbers..and that in itself will be the proof.

[Amir_rulez]

zoom in, u shud be able to see it better. Formulae there, plug in values, get the answer....as simple as that.

[hasanahmad]

ok guys did i do this right? look at pic below

[Amir_rulez]

Close. I didnt see u talk abt equation y=x in ur solution at all. Whats m for this eq? and howz it related to m of the other line?

[tahaqureshi]

All you need to say more is that the gradient of y=x is 1, hence since the gradient of the line concerned is -1, it is perpendicular.