Wing asked in 科學及數學數學 · 7 years ago

maths ~~~~~~

1. x + 3 > 2

X = ______

2. x - 2 > 3

x = ______

3.Write each of the following in algebraic form :

(a) The sum of x and y ( x < y ) is multiplied by their difference .

(b) The square of the difference between x and 3y ( x > 3y ) .

4. 2 ( x + 1 ) > 4

X = _____

5. 7x - 9 > 9x + 7

x = ______

6.Danny has 14 model cars .

(a) As his mother is worried that he will spend too much money on model cars , she proposes the following to Danny :

" The maximum number of model cars that Danny can have is 20 . "

Let the total number of model cars that Danny can have be x .

( i ) Write an inequality to represent this situation .

( ii ) Hence find at most how many more model cars he can have .

(b) However , he makes the following counter - proposal :

" Apart from the condition stated above , I would like the total number of model cars to be greater than 17 . "

( i ) How many model cars can he have under this situation ?

( ii ) Hence find at least how many more model cars he can have .

3 Answers

Rating
  • 土扁
    Lv 7
    7 years ago
    Favorite Answer

    1.

    x + 3 > 2

    x > -1

    =====

    2. x - 2 > 3

    x > 5

    =====

    3.

    (a)

    (x + y)(y - x)

    (b)

    (x - 3y)²

    =====

    4.

    2 ( x + 1 ) > 4

    x + 1 > 2

    x > 1

    =====

    5.

    7x - 9 > 9x + 7

    2x < -16

    x < -8

    =====

    6.

    (a)(i)

    x ≤ 20

    (a)(ii)

    Let n be the number of model cars he can have.

    x ≤ 20

    14 + n ≤ 20

    n ≤ 6

    Hence, he can have at most 6 more model cars.

    (b)(i)

    17 < x ≤ 20

    (b)(ii)

    Let m be the number of model cars he can have.

    x < 17

    14 + m > 17

    m > 3

    Hence, he can have at least 3 more model cars.

    2014-07-14 04:47:04 補充:

    Amendment :

    5.

    (b)(ii)

    Let m be the number of model cars he can have.

    x < 17

    14 + m > 17

    m > 3

    Hence, he can have at least 4 more model cars.

    Source(s): 土扁, 土扁
  • 7 years ago

    可能係電腦功課,就咁 copy 落黎?

  • Lee
    Lv 7
    7 years ago

    點解你咁好心機打入機,不如諗下計左佢。可能花時間仲短。

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