Question

1) (2a+3b)(2a-3b)+9b= 2) (2a+5b)^2-(2a-5b)^2= Срочно!!!

Answer 1

1.(2а+3в)(2а-3в)+9в=4а-6ав+6ав-9в+9в=4а
2.(2а+5в)^2-(2а-5в)^2=4а^2+10в^2-4а^2+10в^2=20в^2
Вроде, так. Хорошего дня.

Answer 2

1) (2a+3b)(2a-3b)+9b=4a^2-9b^2+9b

2) (2a+5b)^2-(2a-5b)^2=4a^2+20ab+25b^2-(4a^2-20ab+25b^2)=

  =4a^2+20ab+25b^2-4a^2+20ab-25b^2=40ab.

Answer 3

Sure, let's solve each of these expressions step-by-step:

1. (2a+3b)(2a-3b) + 9b

To solve this expression, we can use the formula for the difference of squares: (a + b)(a - b) = a^2 - b^2

Applying this formula to the given expression, we get:

(2a + 3b)(2a - 3b) + 9b

= (2a)^2 - (3b)^2 + 9b [Using the difference of squares formula]

= 4a^2 - 9b^2 + 9b

That's the simplified expression.

2. (2a + 5b)^2 - (2a - 5b)^2

To simplify this expression, we can again use the difference of squares formula: (a + b)(a - b) = a^2 - b^2

(2a + 5b)^2 can be expanded as (2a + 5b)(2a + 5b), and (2a - 5b)^2 can be expanded as (2a - 5b)(2a - 5b).

Now let's proceed with the expansion:

(2a + 5b)(2a + 5b) = 4a^2 + 20ab + 25b^2 (2a - 5b)(2a - 5b) = 4a^2 - 20ab + 25b^2

Now, we'll subtract the second expression from the first:

(2a + 5b)^2 - (2a - 5b)^2 = (4a^2 + 20ab + 25b^2) - (4a^2 - 20ab + 25b^2)

The middle terms -20ab and +20ab cancel each other out, leaving us with:

= 4a^2 + 25b^2 - 4a^2 - 25b^2

Now, the 4a^2 and -4a^2 also cancel each other out:

= 25b^2 - 25b^2

Finally, we are left with:

= 0

So, the simplified expression is 0.

If you have any more questions or need further explanations, feel free to ask!