Write each number in standard form 8,000,000+300+9

Using this: a²-b²=(a+b)(a-b)

81x^4-1=

(9x²)²-1=

(9x²-1)(9x²+1)=      (in the bold half we use the formula again)

(3x+1)(3x-1)(9x²+1)

So the answer is D

Answer:

b.

Sacramento School has 1650 students

Ronald E School has 1800 students

c.

Apple Pies cost $4 each

Black Berry Pies cost $19 each

Step-by-step explanation:

b.

Let "x" students attend Sacramento School, and

"y" students attend Ronald E. School

It is given that Sacramento School has 150 fewer students than Ronald E School, so we can write:

x + 150 = y

And,

Total number of students in 2 schools is 3450, we can write:

x + y = 3450

We put Equation 1 in Equation 2 and solve for x first:

Now, we know y = x + 150, y = 1650 + 150 = 1800

So, Sacramento School has 1650 students

Ronald E School has 1800 students

c.

Let apple pies cost "x" and blackberry pies cost "y" each

Gabriella sold 10 apples pies and 12 blackberry pies for total 268, so we can write:

10x + 12y = 268

Also,

Mary sold 14 apple pies and 4 blackberry pies for 132, so we can write:

14x + 4y = 132

Let's multiply Equation 2 with -3, to get:

-3 [14x + 4y = 132]

= -42x - 12y = 396

Lets add this equation to equation 1:

10x + 12y = 268

-42x - 12y = -396

------------------------

-32x = -128

x = -128/-32

x = 4

Now, plugging in x = 4 into 1sst equation, we can solve for y:

10x + 12y = 268

10(4) + 12y = 268

40 + 12y = 268

12 y = 228

y = 228/12

y = 19

So,

Apple Pies cost $4 each

Black Berry Pies cost $19 each