x=2^(a+ 1)=2^a*2

2^a=x/2

y=3+4^a=3+(2^a)^2=3+(x/2)^2

2.

(- 12x^6y^5)÷(-3x^2y^3)

=( 12/3)*x^(6-2)*y^(5-3)

=4x^4y^2

4x^4y^2 square root = plus or minus 2 * x 2 * y

3.

Cylinder volume = 3. 14 * r 2 * h

(1) The radius of the bottom surface is enlarged to 2r, and the cylinder volume is 3.14 * (2r) 2 * h = 4 * (3.14 * r 2 * h).

(2) The height spread is 4h, and the cylinder volume = 3.14 * R2 * 4h = 4 * (3.14 * R2 * h).

4. Read the process of solving the next question and fill in what should be filled in the horizontal line:

If 3x 3-x = 1, what is the value of 9x4+12x3-3x2-7x+1999?

Solution: Because (3x3-x-1) (3x+4) = 9x4+12x3-3x2-7x+1999-2003.

So the algebraic value is (2003). Similarly, can you solve the next problem by solving the above problem?

Given 3x 2-x- 1 = 0, find the value of 6x 3+7x 2-5x+ 1999.

Solution: Because (3x2-x-1) (2x+3) = 6x3+7x2-5x+1999-2002.

So the value of the algebraic expression is (2002)

Analysis:

3x 2 * 2x = 6x 3, make sure that the principal term of x in () is 2x.

(-x) * 2x+3x 2 * 3 = 7x 2, and the constant term in () is determined to be 3.

so- 1 * 3 =-3 = 1999-2002。

6x^3+7x^2-5x+ 1999=(3x^2-x- 1)(2x+3)+2002

The value of the algebraic expression is 2002.