2.6k views

Consider the polynomial $p(x) = a_0 + a_1x + a_2x^2 + a_3x^3$ , where $a_i \neq 0$, $\forall i$. The minimum number of multiplications needed to evaluate $p$ on an input $x$ is:

1. 3
2. 4
3. 6
4. 9
0
By Horner's Rule
+1
Is it in syllabus?
0
we can factorize the equation (x+r1)(x+r2)(x+r3), where r1,r2 and r3 are root of equation
so 3 multiplication
0
Hello reena

Doesn't (x+r1)(x+r2)(x+r3) need 2 multiplication ?

Why're you sure enough that coefficient of $x^{3}$ in our general given equation would be 1 ?

We can use just horner's method, according to which, we can write p(x) as :

$$p(x) = a_0 + x(a_1 + x(a_2 + a_3x))$$

As we can see, here we need only three multiplications, so option (A) is correct.
selected
0

Sir, if the question would be-:

Total number of arithmetic operation required,then answer would be $6(3+3)$.right?

https://gateoverflow.in/2045/gate2014-3-11

+1
@sourav I agree, it should be 6.
a_0+x(a_1+x(a_2+a_3x)) so 3 multiplications required

1
2