tys e maths ques

crucifiedx SG

The temperature at 0900 is -4 degree celsius.

The temperature at 1500 is 14 degree celsius.

Assuming that the temperature rises at a steady rate, find

(i) the temperature at 1300,

(ii) the time when the temperature is 12.5 degree celsius.

for (i), why can't i do like that:

6h - 18 degree celcius

1h - 3 degree celsius

4h - 12 degree celsius

at 1300, -4+12=8 degree celcius?

crucifiedx SG

and this:

y is directly proportional to x^2.

It is known that y=10 for a particular value of x.

Find the value of y when this value of x is halved.

davidche SG

9 am to 1pm ish how many hours?

skythewood SG

y = x^2

when y = 10, x = square root (10)

half this, x = [square root (10)] / 2

x^2 = 10 /4

= 2.5

so y is 2.5

davidche SG

and this:

y is directly proportional to x^2.

It is known that y=10 for a particular value of x.

Find the value of y when this value of x is halved.

y = kx^2

k(x/2)^2 = kx^2 /4 = 1/4 * kx^2

Thus when x is halfed, y is ''quatered''.

haven finish 1/4 *kx^2 = 1/4 y = 1/4 (10) = 2.5

crucifiedx SG

9 am to 1pm ish how many hours?

4 hrs.

eagle SG

The temperature at 0900 is -4 degree celsius.

The temperature at 1500 is 14 degree celsius.

Assuming that the temperature rises at a steady rate, find

(i) the temperature at 1300,

(ii) the time when the temperature is 12.5 degree celsius.

for (i), why can't i do like that:

6h - 18 degree celcius

1h - 3 degree celsius

4h - 12 degree celsius

at 1300, -4+12=8 degree celcius?

I don't see anything wrong with that

crucifiedx SG

i think ans wrong then.. part (ii) how to do?

eagle SG

i think ans wrong then.. part (ii) how to do?

12.5 degrees celcius, means 16.5 degrees change

Continue with your workings

1h - 3 degree celsius
1/6 h - 0.5 degree celsius
33/6 hrs - 16.5 degrees

33/6 hours = 5.5 hours

so 0900 + 5.5 hrs = 1430

maurizio13 SG

does e maths have naperian logarithm?

crucifiedx SG

12.5 degrees celcius, means 16.5 degrees change

Continue with your workings

1h - 3 degree celsius
1/6 h - 0.5 degree celsius
33/6 hrs - 16.5 degrees

33/6 hours = 5.5 hours

so 0900 + 5.5 hrs = 1430

i forgot to add the -4 in my first step. thanks alot. =D

eagle SG

good good...

think you can near B3 to A2 this time round... work hard today and tomorrow

crucifiedx SG

i hope so.. haha. tml can have tuition at 7.30?

eagle SG

should be ok

crucifiedx SG

ok.. i got another ques:

A regular polygon has n sides. The size of each interior angle is 9 times the size of each exterior angle.

(i) calculate the size of each exterior angle.

(ii) hence, find the value of n.

crucifiedx SG

and this: write down the positive square root of 25a^8.

and:

the two sides of a right-angled triangle are of length 1cm and 2cm respectively, find the two possible values of the third side. Leave your answer in the form square root a, where a is a positive integer.

I don't have the answers..

eagle SG

and this: write down the positive square root of 25a^8.

i don't have the answers..

25a^8

= (5a^4)^2

so square root gives you 5a^4

Indices => for square root, take the power divide by 2

skythewood SG

ok.. i got another ques:

A regular polygon has n sides. The size of each interior angle is 9 times the size of each exterior angle.

(i) calculate the size of each exterior angle.

(ii) hence, find the value of n.

interior plus exterior angle = 360?

eagle SG

A regular polygon has n sides. The size of each interior angle is 9 times the size of each exterior angle.

(i) calculate the size of each exterior angle.

(ii) hence, find the value of n.

(i) interior angle + exterior angle = 180°
=> think you can do le

(ii) size of each exterior angle is 360° / n
Use answer from (i) to help solve

skythewood SG

ooo... the whole angle outside is the reflex angle, not exterior angle.