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Solve: 1/2 ("X" + 5) - 1/3 ("X" - 2) = 4 - Mathematics

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Question

Solve: `1/2 ("x" + 5) - 1/3 ("x" - 2) = 4`

Sum

Solution

`1/2 ("x" + 5) - 1/3 ("x" - 2) = 4`

Expand `1/2(x+5): 1/2 (x+5) = x/2 + 5/2`

Expand `1/3 (x-2): 1/3 (x-2) = x/3 - 2/3`

The equation becomes: `x/2+5/2-(x/3 - 2/3) = 4.`

Distribute the negative sign across `x/3 - 2/3`

`x/2 + 5/2-x/3+2/3 = 4`

Group the x-terms and constant terms:

`(x/2-x/3)+(5/2+2/3) = 4`

The least common denominator (LCD) of 2 and 3 is 6. Rewrite the x-terms with a denominator of 6: `x/2 = (3x)/6, x/3 = (2x)/6`

`x/2 - x/3 = (3x)/6 - (2x)/6 = x/6`

Simplify the constant terms

`5/2 = 15/6, 2/3 = 4/6`

Add the constant terms:

`5/2+2/3 = 15/6+4/6=19/6`

`x/6+19/6 =4`

`(x+19)/6=4`

Multiply through by 6: x + 19 = 24.

Subtract 19 from both sides: x = 24 − 19 = 5.

x = 5

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Simple Linear Equations in One Variable
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Chapter 12: Simple Linear Equations (Including Word Problems) - Exercise 12 (C)

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Selina Concise Mathematics [English] Class 7 ICSE
Chapter 12 Simple Linear Equations (Including Word Problems)
Exercise 12 (C) | Q 20

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