Question

—m(9-m) – (4 +m)( m— 4) при m =7_8​

Answer 1

Ответ:

−9m+16

Объяснение:r

1) 9(−m)−(−m)m−(4+m)(m−4)

2) 9(−m)+mm−(4+m)(m−4)

3) 9(−m)+$m^{2}$−(4+m)(m−4)

4) 9(−m)+$m^{2}$  −(4m−16+m  2  −4m)

5) 9(−m)+$m^{2}$ −(−16+$m^{2}$ )

6) 9(−m)+ $m^{2}$ −(−16)−$m^{2}$

7)  9(−m)+$m^{2}$ +16−$m^{2}$

8)  9(−m)+16

9) −9m+16

Answer 2

To evaluate the expression $-m(9-m) - (4 + m)(m - 4)$ when $m = \frac{7}{8}$, first substitute the value of $m$ into the expression and then simplify step by step.

Substituting $m = \frac{7}{8}$ into the expression, we get:

$$-\left(\frac{7}{8}\right)\left(9 - \frac{7}{8}\right) - \left(4 + \frac{7}{8}\right)\left(\frac{7}{8} - 4\right)$$

Now, let's simplify inside the parentheses first:

1. $9 - \frac{7}{8} = \frac{72}{8} - \frac{7}{8} = \frac{65}{8}$

2. $\frac{7}{8} - 4 = \frac{7}{8} - \frac{32}{8} = \frac{-25}{8}$

Substituting these values back into the expression:

$$-\left(\frac{7}{8}\right)\left(\frac{65}{8}\right) - \left(4 + \frac{7}{8}\right)\left(\frac{-25}{8}\right)$$

Now, simplify each part of the expression:

1. $-\left(\frac{7}{8}\right)\left(\frac{65}{8}\right) = -\frac{455}{64}$

2. $\left(4 + \frac{7}{8}\right)\left(\frac{-25}{8}\right) = \left(\frac{33}{8}\right)\left(\frac{-25}{8}\right) = \frac{-825}{64}$

Finally, subtract the second result from the first:

$$-\frac{455}{64} - \frac{-825}{64} = \frac{-455 + 825}{64} = \frac{370}{64} = \frac{185}{32}$$

So, the value of the expression $-m(9-m) - (4 + m)(m - 4)$ when $m = \frac{7}{8}$ is $\frac{185}{32}$ or $5.78125$ when expressed as a decimal.