Question

Now suppose we want to calculate 36+ 25 + 64.
Isn't it easier to add 36 and 64 first?
ut
First write 25 +64 as 64 +25 and then write the full sum
as (36 + 64) + 25.
That is, addition of numbers can be done in any
order.
Now try to find these sums in your head:
49 + 125 + 75
347 +63 + 37
3
88 + 72 + 12
+ 1
+ 2
4
4
15.5 + 0.25 +0.75
8.2 + 3.6 + 6.4​

Answer 1

Answer:

Step-by-step explanation:

$identity \: used \: = (x + a)(x + b) \\ = {x}^{2} + (a + b)x + ab \\ \\ ({4b})^{2} + (9 + 7)4b + 9 \times 7 \\ = {16b}^{2} + (16)4b + 63 \\ = {16b}^{2} + 64b + 63$

Answer:

$3(2x + 1) + 4x + 15 \\ = 6x + 3 + 4x + 15 \\ = 10x + 18 \\ when \: x \: is \: equal \: to \: - 1 \\ = 10 x + 18 \\ = 10( - 1) + 18 \\ = - 10 + 18 \\ = 8$