Add Math Qtns

Y_Shun SG

eagle SG

Depends on question.

Where is the sign?

CoolMyth SG

Your question not very clear. Laughing

Y_Shun SG

It says...

Write down three matries whose sum shows the total number of cusomters in all three restaurant branches who purchased each type of meal on the particular day. Evaluate this total.

HyuugaNeji SG

Originally posted by Y_Shun:
[b]

wrong. A row vector is not a column vector. Try inputting a row vector as a column vector in a computer and your result will be wrong.

Stricly speaking, its wrong(the equation you put up there) but some teachers close one eye.

FireIce SG

Q1. not equal

Q2. plus minus multiply or divide????

Y_Shun SG

wait ar...the thing sot liao Mad

eagle SG

good answer

Y_Shun SG

both signs are negative.

HyuugaNeji SG

it still depends on where you want to put to restuarants (left hand side)(top)
and types of meals. (top)(left hand side)

Y_Shun SG

so its correct or wrong??? it depends on me or what....?

HyuugaNeji SG

At A maths level, you will be marked right. No guarantee though.

It depends on how you define the left and top side. If you define restuarants on the left will become figure A vector.

But if you choose to define type of meals on the left, your restuarant has to be defined on the top, then it will be a figure b vector.

Anyway, most pple just follow what is defined in the question.

For question 2, you can square both sides since these are real numbers.

x^4 - 2x^2 + 1 = x^2 - 2x + 1
x^4 - 3x^2 +2x=0
x(x^3-3x+2)=0
x=0 x=-2 x=1

lpx88 SG

Is that symbol for absolute value?

Y_Shun SG

eagle SG

I think TS did this

(x²-1)² = (x-1)²
(x+1)²(x-1)² - (x-1)² = 0

(x-1)²(x)² = 0
which is wrong

underlined one should then be
(x-1)²(x² + 2x + 1 - 1) = 0
(x-1)²(x)(x+2) = 0

and you get your answer

lpx88 SG

absolute value i thought cant have negative values one?Or im wrong? Confused

Y_Shun SG

seriously, i never even square it leh..i juz remove the aboslute and solve it >_>

HyuugaNeji SG

inside the absolute can have negative. After doing the absolute, cannot have negative.

In this eg, if x=-2
answer will be |3|=|-3|

eagle SG

then you lose a solution

cuz if you want to do that

x²-1 = x-1 or x²-1 = -(x-1)

for x²-1 = x-1
x = 0 or x = 1

for x²-1 = -(x-1)
x=1 or x = -2

you lose the x=-2 solution

^tamago^ SG

abs(x²-1)=abs(x-1)
two absolute functions can be translated as:
f(x)=g(x) or -f(x)=-g(x), and
f(x)=-g(x) or -f(x)=g(x)

x²-1=x-1
x²-x=0
x(x-1)=0
x = 0 or 1

1-x²=x-1
x²+x-2=0
(x+2)(x-1)=0
x = 1 or -2