Question

the only solution to x² + bx + c = 0
is x = 5

work out the values of b and c​

Answer 1

Answers:

b = -10

c = 25

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Explanation:

If x = 5 is the only solution then (x-5) is the only factor. Turns out we have repeated solutions and repeated factors. Meaning (x-5)(x-5) = (x-5)^2 is what we're after.

Expand that out to get

(x-5)^2

x^2 - 5x - 5x + 25

x^2 - 10x + 25

Then compare this to x^2 + bx + c to find

b = -10

c = 25

If you were to solve x^2-10x+25 = 0, you'll find that x = 5 is the only root.