The function f is defined by f(x)=x^2+3x-10

If f(x+5)=x^2+kx+30, k=____ Find the smallest zero of f(x+5). x=____

1 answer

To find k, we need to expand f(x+5) using the given function f(x) = x^2 + 3x - 10.

f(x+5) = (x+5)^2 + 3(x+5) - 10
f(x+5) = x^2 + 10x + 25 + 3x + 15 - 10
f(x+5) = x^2 + 13x + 30

Comparing this to x^2 + kx + 30, we can see that k = 13.

To find the smallest zero of f(x+5), we set f(x+5) equal to zero and solve for x:

x^2 + 13x + 30 = 0

This is a quadratic equation that can be factored as:

(x + 3)(x + 10) = 0

Setting each factor to zero gives us the solutions x = -3 or x = -10. The smallest zero is x = -10.