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Transcript

PRESENTATION

Problem solving

Step 6

Step 5

Step 4

Step 3

Step 2

Step 1

Index

When seven times a certain number is subtracted from 15, the result is -4.Find the number.

01

Decide the unknown quantity and allocate a pronumeral

Let x be the number

Decide which operations are involved

02

So the equation is : 15 - 7x = -4

When :

"... the result is -4. " --> -4

"... is substracted from 15..." --> 15 - 7x

"...seven times a certain number..." --> 7x

We explain the equation

03

Translate the problem into a linear equation by isolating the pronumeral

So the linear equation is : 15 + 4 = 7x

15 - 7x + 4 = 0

15 - 7x + 4 = -4 + 4

15 - 7x = -4

15 - 7x + 7x + 4 = 0 + 7x

Transform in a linear equation

04

Solve the linear equation by isolating the pronumeral

15 + 4 = 7x19 = 7x19 / 7 = 7x / 719/7 = xThe result is 19/7

Solve the equation

05

Check that the result does solve the initial problem

We replace "x" by 19/715 -7x = -415 - 7 * 19/7 = -415 - 19 = -4-4 = -4

Check the result

Write your answer in sentence form

06

Write your answer in sentence form. Remember, there is usually no pronumeral in the original problem

Give the answer

The number is 19/7 because :15 - 7 * 19/7 = -4

Exemple

07

Write your answer in sentence form. Remember, there is usually no pronumeral in the original problem

Exemple

32/4+2x = 138/3

Exemple

32/4+2x = 138/38+2x = 362x = 36-82x = 28

Exemple

32/4+2x = 138/38+2x = 362x = 36-82x = 282x/2 = 28/2x = 14

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