Q25 A train travelling at a speed of 30km/h crosses a bridge 25m long in 12 sec. How long will it take to overtake a another tra
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Geez this is a doozy
okay first factor the binomial using binomial theorem. you probably don't remember that (at least I didn't) so here it is.
you have to figure out what two numbers add to -17 and multiply together to make 72
so make a table of all the numbers that add to 17 then multiply them together and see of they make 72. since it's -17 we will need to use two negative numbers:
-1 * -16 = 16
-2 * -15 = 30
-3 * -14 = 42? idk
-4 * -13 = something, math is hard
keep going until...
-8 * -9 = 72
so it's -8 and -9 are the factors we want.
we wrote this as:
seeing this equal as our area in the a=l*w formula gives:
Now, plug in a number greater than 9.
It has to be greater than 9 because anything less than that would give us a negative area. Let's use 10 because it's easy. It doesn't matter which number you use as long as it's greater than 10. The problem appears to say it just wants a possible length and width, not a specific answer.
so factors of 2.
length could be 1 and width could be 2 or vice versa.
you could also choose a different number than 10. let's try 20.
so lw could also be 10 and 3 in this case. or 5 and 6. or 1 and 30. all these answers would be correct.
okay first factor the binomial using binomial theorem. you probably don't remember that (at least I didn't) so here it is.
you have to figure out what two numbers add to -17 and multiply together to make 72
so make a table of all the numbers that add to 17 then multiply them together and see of they make 72. since it's -17 we will need to use two negative numbers:
-1 * -16 = 16
-2 * -15 = 30
-3 * -14 = 42? idk
-4 * -13 = something, math is hard
keep going until...
-8 * -9 = 72
so it's -8 and -9 are the factors we want.
we wrote this as:
seeing this equal as our area in the a=l*w formula gives:
Now, plug in a number greater than 9.
It has to be greater than 9 because anything less than that would give us a negative area. Let's use 10 because it's easy. It doesn't matter which number you use as long as it's greater than 10. The problem appears to say it just wants a possible length and width, not a specific answer.
so factors of 2.
length could be 1 and width could be 2 or vice versa.
you could also choose a different number than 10. let's try 20.
so lw could also be 10 and 3 in this case. or 5 and 6. or 1 and 30. all these answers would be correct.