Slot method
20 options
3 slots
First slot: 20 options
Second slot: 19 options (one used up for 1st slot)
Third slot: 18 (one less than last)
Multiply them
20 times 19 times 18=6840
Answer is 6840 ways
Answer:
80+80=160
Step-by-step explanation:
Answer:
A
Step-by-step explanation:
In this question, we are concerned with selecting which of the options best represents the difference of two squares.
Let’s have an exposition below as follows;
Consider two numbers, which are perfect squares and can be expressed as a square of their square roots;
a^2 and b^2
where a and b represents the square roots of the numbers respectively.
Inserting a difference between the two, we have;
a^2 - b^2
Now by applying the difference of two squares, these numbers will become;
a^2 - b^2 = (a + b)(a-b)
So our answer out of the options will be that option that could be expressed as above.
The correct answer to this is option A
Kindly note that;
x^2 -9 can be expressed as x^2 - 3^2 and consequently, this can be written as;
(x-3)(x + 3)
