O-Level Additional Math

[Sahimi]

Augmum:

Sahimi:

Hi pls help!


The two parallel sides of a trapezium are 3x and (5x + 8)cm each. Given the height between the parallel lines is (x - 1)cm. Show that the area is 4(x2 - 1).

hi
let me try to attempt yr question.

Area of trapezium = half the sum of parallel lines x height = ½ X (3x +5x+ 8 ) x (x-1)
=8x+8 / 2 X (x-1)
=2(4x + 4)/2 X (x-1)
=(4x + 4) (x-1)
= 4 (x+1) (x-1)
=4 (x2 –x+x-1)
=4 (x2-1) (Ans)

thks v.m

[Guan Hui]

Sahimi:

Pls help !


Q1) Given that x2 + y2 = 185 and xy = -12, find the value of (x - y)2

Q2) If (a - b)2 = 72 and ab = 8.5, calculate the value of a2 + b2.

Q3) Given that 1043square - 1037square = 120y, find value the y without using calculator.

1)(x-y)^2=x^2-2xy+y^2
= x^2+y^2-2xy
= 185-2(-12)
=185+24
=209

2) you may want to try to do it using q1 method

3)using (x+y)(x-y)=x^2-y^2
1043^2-1037^2=(1043+1037)(1043-1037)
=(2080)(6)
=(208)(60)
=(104)(120)
=120y
therefore y= 104

[leesf]

suiyuan:

Hi Teacher Guan Hui


Please help.

1)Mrs Lee has 2 daughters,Alice and Judy.The highest common factor and lowest common multiple of their ages are 3 and 168 respectively.If Alice is 3 years older than her sister, find her age.

2)The HCF and LCM of 270 and A are 18 and 5940 respectively. What is the value of A?

Thank you

Answer given for 2nd question in this thread was 396. My child got this question for his homework & I showed him the working but his teacher marked it wrong. Anyone can help? TIA

[Sahimi]

Guan Hui:

Sahimi:

Pls help !


Q1) Given that x2 + y2 = 185 and xy = -12, find the value of (x - y)2

Q2) If (a - b)2 = 72 and ab = 8.5, calculate the value of a2 + b2.

Q3) Given that 1043square - 1037square = 120y, find value the y without using calculator.

1)(x-y)^2=x^2-2xy+y^2
= x^2+y^2-2xy
= 185-2(-12)
=185+24
=209

2) you may want to try to do it using q1 method

3)using (x+y)(x-y)=x^2-y^2
1043^2-1037^2=(1043+1037)(1043-1037)
=(2080)(6)
=(208)(60)
=(104)(120)
=120y
therefore y= 104

thks v.m :lol:

[Guan Hui]

leesf:

suiyuan:

Hi Teacher Guan Hui


Please help.

1)Mrs Lee has 2 daughters,Alice and Judy.The highest common factor and lowest common multiple of their ages are 3 and 168 respectively.If Alice is 3 years older than her sister, find her age.

2)The HCF and LCM of 270 and A are 18 and 5940 respectively. What is the value of A?

Thank you

Answer given for 2nd question in this thread was 396. My child got this question for his homework & I showed him the working but his teacher marked it wrong. Anyone can help? TIA

Hello... I guess the teacher is wrong>.>

[OK Lor]

Hi Sir,


:welcome: :celebrate:

[Guan Hui]

wassup

de email notification sort of stop and was having quite alot of things on hand so was unactive for the last few months.

[beautifulalps]

Hello Teacher, pls help us.

(-2)^5x(-3)4(-5)+(-6)^2-(-7)( - 8 )

this answer must be 8. But i could not solve that answer. There is something wrong. :stupid:

[iFruit]

beautifulalps:

Hello Teacher, pls help us.

(-2)^5x(-3)4(-5)+(-6)^2-(-7)( - 8 )

this answer must be 8. But i could not solve that answer. There is something wrong. :stupid:

It should perhaps be

(-2)^5 + (-3)4(-5)+(-6)^2 -(-7)( - 8 )

[Guan Hui]

iFruit:

beautifulalps:

Hello Teacher, pls help us.

(-2)^5x(-3)4(-5)+(-6)^2-(-7)( - 8 )

this answer must be 8. But i could not solve that answer. There is something wrong. :stupid:

It should perhaps be

(-2)^5 + (-3)4(-5)+(-6)^2 -(-7)( - 8 )

beautifulalps
for your question ans shd be -1900 if i am not wrong
-32*60+36-56=-1900
maybe you copy it wrongly?

I think ifruit is correct
-32+60+36-56=8
which give you the ans you want=D