Question

If z = 10, find the value of ${z^3} - 3\left( {z - 10} \right)$.

Answer 1

Hint:
Put the value of z = 10 in ${z^3} - 3\left( {z - 10} \right)$ to find the required solution.

Complete step by step solution:
Given z =10
Now ${z^3} - 3\left( {z - 10} \right)$
 $ \Rightarrow {z^3} - 3z + 30$
Putting z = 10
 $ \Rightarrow {\left( {10} \right)^3} - 3 \times 10 + 30 = 1000$
On solving we get
 ${z^3} - 3\left( {z - 10} \right) = 1000$

So, thousand is the correct answer.

Note:
Sometimes this question required factorization to solve them.
Example if expression is ${x^2} - 7x + 10$
Then it can be written as
  ${x^2} - 2x - 5x + 10$
 $ = x\left( {x - 2} \right) - 5\left( {x - 2} \right)$
 $ = \left( {x - 2} \right)\left( {x - 5} \right)$
Now we can directly find the answer after putting the value of x in this expression.