Factoring in real numbers, x-3x + X________

Factoring in real numbers, x-3x + X________

If the expression is not clear, write it again

On the mathematical problems of Qin Jiushao's algorithm
This paper lists the polynomial f (x) = x ^ 6 + 2x ^ 5 + 3x ^ 4 + 5x ^ 2 + 6x + 7 according to Qin jiuzhao's algorithm, and explains that this algorithm has done several times of multiplication and addition, which represents the x power of the number, and F is the first power of the number

f(x)=x^6+2x^5+3x^4+5x^2+6x+7
=x(x^5+2x^4+3x^3+5x+6)+7
=x(x(x^4+2x^3+3x^2+5)+6)+7
=x(x(x*x(x^2+2x+3)+5)+6)+7
=x(x(x*x(x(x+2)+3)+5)+6)+7
There are 5 times of addition and 5 times of multiplication, in which multiplication has two times of multiplication

When calculating the value of polynomial f (x) = 12 + 35x-8x2 + 79x3 + 6x4 + 5x5 + 3x6 in x = - 4 with Qin Jiushao algorithm, the value of V3 is ()
A. -845B. 220C. -57D. 34

∵ f (x) = 12 + 35x-8x2 + 79x3 + 6x4 + 5x5 + 3x6 = ((3x + 5) x + 6) x + 79) X-8) x + 35) x + 12, ∵ V0 = A6 = 3, V1 = v0x + A5 = 3 × (- 4) + 5 = - 7, V2 = V1x + A4 = - 7 × (- 4) + 6 = 34, V3 = v2x + a3 = 34 × (- 4) + 79 = - 57, and the value of V3 is - 57; therefore, C