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The zeroes of f(x) = x2 – 8x + 17 are?

User LEO CHEN
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1 Answer

5 votes

Answer:

No zeros

Explanation:

we have to solve the equation x² – 8x + 17 = 0 ,in order to determine The zeroes of f.

Method 1 :

x² – 8x + 17 = 0

The discriminant Δ = (-8)² – 4 × 1 × 17 = 64 − 68 = −4

Since Δ < 0 then the equation has no solutions

Thus, f has no zeros.

Method 2 :

x² – 8x + 17 = x² – 2(x)(4) + 16 – 16 + 17

= x² – 2(x)(4) + 16 – 16 + 17

= x² – 2(x)(4) + 4² – (17 - 16)

= (x - 4)² + 1

Then

x² – 8x + 17 = 0

⇔ (x - 4)² + 1 = 0

⇔ (x - 4)² = -1 (impossible)

Which means ,f has no zeros.

User David Snabel
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