Question

3/4 (х+2)+2/5 (х-1)=21/40

Answer 1

Ответ:

Объяснение:

3/4 (х+2)+2/5 (х-1)=21/40

3/4x + 1 1/2 + 2/5x - 2/5 = 21/40

0,75x + 1,5 + 0,4x - 0,4 = 0,021

1,15x + 0,9 = 0,021

1,15x = -0,879

x = 74/115

Ответ: 74/115

Answer 2

To solve the equation:

$\frac{3}{4}(x + 2) + \frac{2}{5}(x - 1) = \frac{21}{40}$

You can start by clearing the fractions by finding a common denominator. In this case, the common denominator would be 20.

So, multiply every term in the equation by 20 to eliminate the fractions:

$20 \cdot \left(\frac{3}{4}(x + 2)\right) + 20 \cdot \left(\frac{2}{5}(x - 1)\right) = 20 \cdot \left(\frac{21}{40}\right)$

Now, simplify each term:

$15(x + 2) + 8(x - 1) = \frac{21}{2}$

Next, distribute the numbers:

$15x + 30 + 8x - 8 = \frac{21}{2}$

Combine like terms:

$23x + 22 = \frac{21}{2}$

Now, subtract 22 from both sides of the equation:

$23x = \frac{21}{2} - 22$

To subtract fractions, they need a common denominator, which in this case is 2:

$23x = \frac{21}{2} - \frac{44}{2}$

Now, subtract the fractions:

$23x = -\frac{23}{2}$

Finally, divide both sides by 23 to solve for x:

$x = \frac{-23}{2 \cdot 23}$

Simplify:

$x = \frac{-1}{2}$

So, the solution to the equation is $x = -\frac{1}{2}$.