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Vieta's Formulas for Polynomials: all problems

Focus mode: every practice problem from the chapter, one after another.

0 / 25 solved

Problem 13.2.1

Find the sum and product of the roots of the quadratic 2x2−24x+172x^2 - 24x + 17.

Problem 13.2.2

AMC 12

There are two values of aa for which the equation 4x2+ax+8x+9=04x^2 + ax + 8x + 9 = 0 has only one solution for xx. What is the sum of these values of aa?

P(x) = 4x² + 8x + 9; roots −1 + 1.118i, −1 − 1.118i; sum of roots −2, product 9/4

a4
b8
c9
P(x)=4(x2+2x+94)=4x2+8x+9P(x) = 4(x^{2} + 2x + \frac{9}{4}) = 4x^{2} + 8x + 9
r1,r2=−2±5i2r_1, r_2 = \frac{-2 \pm \sqrt{5}i}{2}
sumr1+r2=−ba=−84=−2r_1 + r_2 = -\frac{b}{a} = -\frac{8}{4} = -2
productr1r2=ca=94=94r_1r_2 = \frac{c}{a} = \frac{9}{4} = \frac{9}{4}
discriminantb2−4ac=(8)2−4(4)(9)=−80b^2 - 4ac = (8)^2 - 4(4)(9) = -80no real roots: a complex pair

P(x) = 4x² + 8x + 9; roots −1 + 1.118i, −1 − 1.118i; sum −2; product 9/4; discriminant −80: no real roots: a complex pair

Problem 13.2.3

AMC 10

Let aa and bb be the roots of the equation x2−mx+2=0x^2 - mx + 2 = 0. Suppose that a+1ba + \frac{1}{b} and b+1ab + \frac{1}{a} are the roots of the equation x2−px+q=0x^2 - px + q = 0. What is qq?

Problem 13.2.4

AMC 10/12

A rectangular box P\mathcal{P} has distinct edge lengths aa, bb, and cc. The sum of the lengths of all 1212 edges of P\mathcal{P} is 1313, the sum of the areas of all 66 faces of P\mathcal{P} is 112\frac{11}{2}, and the volume of P\mathcal{P} is 12\frac{1}{2}. What is the length of the longest interior diagonal connecting two vertices of P\mathcal{P}?

Problem 13.2.5

AMC 12

For how many ordered pairs (a,b)(a, b) of integers does the polynomial x3+ax2+bx+6x^3 + ax^2 + bx + 6 have 33 distinct integer roots?

P(x) = x³ − 4x² + x + 6; roots −1, 2, 3; sum of roots 4, product −6

Degree3
Lead a1
r₁r₂r₃
P(x)=(x+1)(x−2)(x−3)=x3−4x2+x+6P(x) = (x + 1)(x - 2)(x - 3) = x^{3} - 4x^{2} + x + 6
r1=−1,  r2=2,  r3=3r_1 = -1,\; r_2 = 2,\; r_3 = 3
sumr1+r2+r3=−ba=−−41=4r_1 + r_2 + r_3 = -\frac{b}{a} = -\frac{-4}{1} = 4
sum of products of 2r1r2+r1r3+r2r3=ca=11=1r_1r_2 + r_1r_3 + r_2r_3 = \frac{c}{a} = \frac{1}{1} = 1
productr1r2r3=−da=−61=−6r_1r_2r_3 = -\frac{d}{a} = -\frac{6}{1} = -6

P(x) = x³ − 4x² + x + 6; roots −1, 2, 3; sum 4; product −6

Problem 13.2.6

AMC 10

What is the sum of the reciprocals of the roots of the equation 20032004x+1+1x=0\frac{2003}{2004}x + 1 + \frac{1}{x} = 0?

Problem 13.2.7

AMC 10

The quadratic equation x2+mx+nx^2 + mx + n has roots twice those of x2+px+mx^2 + px + m, and none of mm, nn, and pp is zero. What is the value of np\frac{n}{p}?

Problem 13.2.8

AMC 10

Let ff be a function for which f(x3)=x2+x+1f\left(\frac{x}{3}\right) = x^2 + x + 1. Find the sum of all values of zz for which f(3z)=7f(3z) = 7.

Problem 13.2.9

AMC 10

What is the sum of all real numbers xx for which ∣x2−12x+34∣=2|x^2 - 12x + 34| = 2?

Problem 13.2.10

AMC 10

The polynomial x3−ax2+bx−2010x^3 - ax^2 + bx - 2010 has three positive integer roots. What is the smallest possible value of aa?

Problem 13.2.11

AMC 10

Suppose that aa and bb are nonzero real numbers, and that the equation x2+ax+b=0x^2 + ax + b = 0 has solutions aa and bb. Then the pair (a,b)(a, b) is

Click a choice or type its letter (A–E).

Problem 13.2.12

AIME

Suppose that the roots of x3+3x2+4x−11=0x^3 + 3x^2 + 4x - 11 = 0 are aa, bb, and cc, and that the roots of x3+rx2+sx+t=0x^3 + rx^2 + sx + t = 0 are a+ba + b, b+cb + c, and c+ac + a. Find tt.

Problem 13.2.13

AMC 10

For certain real numbers aa, bb, and cc, the polynomial

g(x)=x3+ax2+x+10g(x) = x^3 + ax^2 + x + 10

has three distinct roots, and each root of g(x)g(x) is also a root of the polynomial

f(x)=x4+x3+bx2+100x+c.f(x) = x^4 + x^3 + bx^2 + 100x + c.

What is f(1)f(1)?

Problem 13.2.14

AMC 10

Let aa, bb, and cc be three distinct one-digit numbers. What is the maximum value of the sum of the roots of the equation (x−a)(x−b)+(x−b)(x−c)=0(x - a)(x - b) + (x - b)(x - c) = 0?

Problem 13.2.15

AMC 10

All the roots of the polynomial z6−10z5+Az4+Bz3+Cz2+Dz+16z^6 - 10z^5 + Az^4 + Bz^3 + Cz^2 + Dz + 16 are positive integers, possibly repeated. What is the value of BB?

Problem 13.2.16

AMC 10/12

This problem also appears in the book as 13.2.15.

All the roots of polynomial z6−10z5+Az4+Bz3+Cz2+Dz+16z^6 - 10z^5 + Az^4 + Bz^3 + Cz^2 + Dz + 16 are positive integers, possibly repeated. What is the value of BB?

Problem 13.2.17

AMC 12A

Let aa, bb, and cc be the roots of the polynomial x3+kx+1x^3 + kx + 1. What is the sum

a3b2+a2b3+b3c2+b2c3+c3a2+c2a3?a^3b^2 + a^2b^3 + b^3c^2 + b^2c^3 + c^3a^2 + c^2a^3?

(Give your answer in terms of kk.)

Problem 13.2.18

USAMOChallenge

In the polynomial x4−18x3+kx2+200x−1984=0x^4 - 18x^3 + kx^2 + 200x - 1984 = 0, the product of 22 of its roots is −32-32. Find kk.

Problem 13.3.1(additional)

AMC 10

The zeros of the function f(x)=x2−ax+2af(x) = x^2 - ax + 2a are integers. What is the sum of the possible values of aa?

Problem 13.3.2(additional)

AIME

Let rr, ss, and tt be the three roots of the equation

8x3+1001x+2008=0.8x^3 + 1001x + 2008 = 0.

Find (r+s)3+(s+t)3+(t+r)3(r + s)^3 + (s + t)^3 + (t + r)^3.

Problem 13.3.3(additional)

AIME

Find the sum of the roots, real and non-real, of the equation x2001+(12−x)2001=0x^{2001} + \left(\frac12 - x\right)^{2001} = 0, given that there are no multiple roots.

Problem 13.3.4(additional)

AHSME

How many distinct ordered triples (x,y,z)(x, y, z) satisfy the following equations?

x+2y+4z=12x + 2y + 4z = 12
xy+4yz+2xz=22xy + 4yz + 2xz = 22
xyz=6xyz = 6

Problem 13.3.5(additional)

AIMEChallenge

Consider the polynomials P(x)=x6−x5−x3−x2−xP(x) = x^6 - x^5 - x^3 - x^2 - x and Q(x)=x4−x3−x2−1Q(x) = x^4 - x^3 - x^2 - 1. Given that z1z_1, z2z_2, z3z_3, and z4z_4 are the roots of Q(x)=0Q(x) = 0, find P(z1)+P(z2)+P(z3)+P(z4)P(z_1) + P(z_2) + P(z_3) + P(z_4).

Problem 13.3.6(additional)

AIMEChallenge

For integers aa, bb, cc and dd, let f(x)=x2+ax+bf(x) = x^2 + ax + b and g(x)=x2+cx+dg(x) = x^2 + cx + d. Find the number of ordered triples (a,b,c)(a, b, c) of integers with absolute values not exceeding 1010 for which there is an integer dd such that g(f(2))=g(f(4))=0g(f(2)) = g(f(4)) = 0.

Problem 13.3.7(additional)

AIMEChallenge

Let P(x)=x2−3x−7P(x) = x^2 - 3x - 7, and let Q(x)Q(x) and R(x)R(x) be two quadratic polynomials also with the coefficient of x2x^2 equal to 11. David computes each of the three sums P+QP + Q, P+RP + R, and Q+RQ + R and is surprised to find that each pair of these sums has a common root, and these three common roots are distinct. If Q(0)=2Q(0) = 2, then R(0)=mnR(0) = \frac{m}{n}, where mm and nn are relatively prime positive integers. Find m+nm + n.