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STUCK at maths grade 9 questions

hi I'm gonna post the grade 9 questions I found, I'm struggling to do them, they don't even have a markscheme, btw its a NON CALCULATOR paper

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OP

here are the questions

Study Forum Helper

Original post by usernamenew

here are the questions

I'll start with the first question.

You should recognise that

(a-bx)(a+bx)

is the difference between two squares. How can you expand the expression from there? :smile:

:smile:

Kevin De Bruyne

Original post by usernamenew

here are the questions

Hint for 2: 0.16 expressed as a fraction is...

(Why are 16 and 100 such nice numbers?)

OP

Original post by usernamenew

here are the questions

i would appreciate if i could get any help on any of the questions tbh

90909090908.PNG5.5KB

9090909.PNG26.5KB

90090.PNG15.6KB

in the first part expand the brackets and equate similar x terms.
in the triangle- use the cosine formula ( a^2 = b^2 + c^2 - 2bc cos A)

OP

Original post by Kevin De Bruyne

Hint for 2: 0.16 expressed as a fraction is...

(Why are 16 and 100 such nice numbers?)

haha yeh i realised that, i was thinking you would just have to square root, but is that it?

Study Forum Helper

Original post by usernamenew

i would appreciate if i could get any help on any of the questions tbh

Let's stick with a few questions at a time :smile:

:smile:

OP

Original post by _gcx

I'll start with the first question.

You should recognise that

(a-bx)(a+bx)

is the difference between two squares. How can you expand the expression from there? :smile:

:smile:

tthank you, i can do that but what does it mean by b to the minus a?

Study Forum Helper

Original post by usernamenew

tthank you, i can do that but what does it mean by b to the minus a?

Have you found

a

and

b

? If so, it's just a matter of substitution :smile:

:smile:

OP

Original post by _gcx

Let's stick with a few questions at a time :smile:

:smile:

yeh sorry about that

Study Forum Helper

Original post by usernamenew

haha yeh i realised that, i was thinking you would just have to square root, but is that it?

No, the exponent is 1.5 (

\frac{3}{2}

) not 0.5 (

\frac{1}{2}

). Note that

a^{\frac{3}{2}} \equiv (a^{\frac{1}{2}})^3 \equiv (\sqrt{a})^3

, here.

:smile:

OP

Original post by _gcx

Have you found

a

and

b

? If so, it's just a matter of substitution :smile:

:smile:

i dont think i have. i tried expanding the bracket i got ax^ - b^x3
( idk how to write it properly)

Kevin De Bruyne

Original post by usernamenew

haha yeh i realised that, i was thinking you would just have to square root, but is that it?

Apologies - I shouldn't have posted that hint... I am too eager!

I think it's easier for you when there is only one person helping and you are tackling one question at a time so I'll bow out...

All the best.

OP

Original post by _gcx

No, the exponent is 1.5 (

\frac{3}{2}

) not 0.5 (

\frac{1}{2}

). Note that

a^{\frac{3}{2}} \equiv (a^{\frac{1}{2}})^3 \equiv (\sqrt{a})^3

, here.

:smile:

thank you so much. so is this right 10³
over 4³so 1000/64

OP

Original post by Kevin De Bruyne

Apologies - I shouldn't have posted that hint... I am too eager!

I think it's easier for you when there is only one person helping and you are tackling one question at a time so I'll bow out...

All the best.

aw thank you, its ok, i dont mind. its your choice :smile:

:smile:

Study Forum Helper

Original post by usernamenew

i dont think i have. i tried expanding the bracket i got ax^ - b^x3
( idk how to write it properly)

Did you mean

a^2x - b^2x^3

?

:smile:

If so, that's correct.

If you know that

a^2x - b^2x^3 = 25x - 4x^3

, what is

a

and

b

, and hence what is

b^{-a}

?

Where did you find these and do you have answers?

Study Forum Helper

Original post by usernamenew

thank you so much. so is this right 10³
over 4³so 1000/64

Yes, though I'd aim to write the fraction in its simplest form :smile:

:smile:

OP

Original post by _gcx

Did you mean

a^2x - b^2x^3

?

:smile:

If so, that's correct.

If you know that

a^2x - b^2x^3 = 25x - 4x^3

, what is

a

and

b

, and hence what is

b^{-a}

?

yeh made a silly mistake :colondollar:

:colondollar:

so im guessing you have to factorise? or am i wrong?

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