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           ☆1 equations

[ 1/1 Equation]
    Work: Find the solution of equation (0.85-0.0075x)(1.3+0.015x)-1 = 0 .
    Question type: Equation
    Solution:Original question:

(

17 20

−

3 400

x

)

(

13 10

+

3 200

x

)

−

1

=

0

    Remove the bracket on the left of the equation:

Left side of the equation =

17 20

(

13 10

+

3 200

x

)

−

3 400

x

(

13 10

+

3 200

x

)

−

1

=

17 20

×

13 10

+

17 20

×

3 200

x

−

3 400

x

(

13 10

+

3 200

x

)

−

1

=

221 200

+

51 4000

x

−

3 400

x

(

13 10

+

3 200

x

)

−

1

=

21 200

+

51 4000

x

−

3 400

x

(

13 10

+

3 200

x

)

=

21 200

+

51 4000

x

−

3 400

x

×

13 10

−

3 400

x

×

3 200

x

=

21 200

+

51 4000

x

−

39 4000

x

−

9 80000

x

x

=

21 200

+

3 1000

x

−

9 80000

x

x

    The equation is transformed into :

21 200

+

3 1000

x

−

9 80000

x

x

=

0

    After the equation is converted into a general formula, it is converted into:
    ( x + 20 )( 3x - 140 )=0
    From
        x + 20 = 0
        3x - 140 = 0
    it is concluded that:：
        x₁=-20

x2=

140 3

    
    There are 2 solution(s).

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