O-Level Additional Math

[awesomeguy]

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I know the answer for part (a), 3000cm3 but I don't know how to do parts (b) and (c). Each part is 2 marks each. Thanks! :? :? :?
bigger image: http://i45.tinypic.com/2zrqf60.jpg

[Jtutor]

Hi awesomeguy!


Allow me to help you:

(b) angle DBC = angle BCP (alt angles)
tan angle DBC = 15/20
angle DBC = 36.9 degrees = angle BCP

Area of triangle BCD = 1/2 x 15 x 20 = 150cm^2
Find the length of BD => 25cm (Pythagoras’ theorem)
Use common area of triangle:
1/2 x BD x Vertical Height = 150
1/2 x 25 x h = 150
h = 12cm

Cheers!

[awesomeguy]

Jtutor:

Hi awesomeguy!


Allow me to help you:

(b) angle DBC = angle BCP (alt angles)
tan angle DBC = 15/20
angle DBC = 36.9 degrees = angle BCP

(c) Area of triangle BCD = 1/2 x 15 x 20 = 150cm^2
Find the length of BD => 25cm (Pythagoras' theorem)
Use common area of triangle:
1/2 x BD x Vertical Height = 150
1/2 x 25 x h = 150
h = 12cm

Cheers!

:thankyou:
Thanks Jtutor!
:thankyou:

[Jtutor]

You are most welcome

[Herbie]

Hi jtutor, pls check yr pm

[beauty queen]

can u pls help me to solve this problem…


Given that(5x^3-4x^2+6x-2)=(x+3)(x-4)Q(x)+Ax+B where Q(x) is a polynominal, find the value of A and of B

Thank you

[beauty queen]

can u pls help me to solve this problem…


Given that(5x^3-4x^2+6x-2)=(x+3)(x-4)Q(x)+Ax+B where Q(x) is a polynominal, find the value of A and of B

Thank you

[beauty queen]

anyone can u pls help me to solve this problem..


Given that(5x^3-4x^2+6x-2)=(x+3)(x-4)Q(x)+Ax+B where Q(x) is a polynominal, find the value of A and of B

Thank you :thankyou:

[Xiao Hu]

beauty queen:

can u pls help me to solve this problem..


Given that(5x^3-4x^2+6x-2)=(x+3)(x-4)Q(x)+Ax+B where Q(x) is a polynominal, find the value of A and of B

Thank you

Try substituing x=-3 and x=4 into the equation. These values of x come from trying to make the factors of (x+3) and (x-4) to become zeros, so that we don't have to worry about Q(x) as that part of the expression becomes 0. Then you would obtain 2 equations with A and B, which should be able to solve.

Regards,
Xiao hu.

[dazzlego]

beauty queen:

anyone can u pls help me to solve this problem..


Given that(5x^3-4x^2+6x-2)=(x+3)(x-4)Q(x)+Ax+B where Q(x) is a polynominal, find the value of A and of B

Thank you :thankyou:

Hi beauty queen,

There are 2 ways to solve this question.

1. Using Remainder Theorem
If the polynomial f(x) is divided by (ax-b), the remainder is f(b/a)

In this case, f(x) is (5x^3-4x^2+6x-2)
And when f(x) is divided by (x+3) or (x-4), the remainder will be Ax+B.

In other words, f(-3) = -3A+B and f(4) = 4A+B
f(-3) = 5*(-27) - 4*9 + 6*(-3) - 2 = - 191
f(4) = 5*64 - 4*16 + 6*4 - 2 = 278

-3A + B = -191
4A + B = 278
Solve the simultaneous equations to get A=67 and B=10

2. Using Long Division
Divided (5x^3-4x^2+6x-2) by (x^2 - x - 12) will give you (5x+1) remainder 67x+10
(5x+1) is Q(x) and (67x+10) is Ax+B

Cheers :celebrate: