Question

Determine os zeros da função: f(x) = x2 – 7x + 10.

(A) x1= 2 e x2= 5.

(B) x1= 2 e x2= 7.

(C) x1= 2 e x2= 10.

(D) x1= 7 e x2= 5.

(E) x1= 10 e x2= 5.

Answer 1

Resposta:

Letra A

Explicação passo-a-passo:

f(x) = x² – 7x + 10

x² -7x + 10 = 0

a=1

b=-7

c=10

Δ=b²-4ac

Δ=(-7)² -4(1)(10)

Δ = 49 - 40

Δ = 9

$x={-b\pm\sqrt{\Delta} \over2a}\\ \\ x={-(-7)\pm\sqrt{9} \over2(1)}={7\pm3\over2}\\ \\ x_1={7-3\over2}={4\over2}=2\\ \\ x_2={7+3\over2}={10\over2}=5$