113k views
1 vote
What is the solution set of x2 – 10 = 30x?

{–220, 250}
{–250, 220}
{15 – StartRoot 235 EndRoot, 15 + StartRoot 235 EndRoot}
{–15 – StartRoot 235 EndRoot, –15 + StartRoot 235 EndRoot}

2 Answers

1 vote

Answer:

C

Explanation:

User Maks Matsveyeu
by
4.5k points
1 vote

9514 1404 393

Answer:

(c) {15 -√235, 15 +√235}

Explanation:

For solutions p and q, the trinomial is ...

(x -p)(x -q) = x² -(p+q)x +pq

That is, the constant term (-10) must be the product of the roots, and the x-coefficient (-30) must be the opposite of their sum.

The sums of roots in the answer choices are ...

a) 30

b) -30

c) 30

d) -30

We know the sum of roots is 30, so we can eliminate choices 'b' and 'd'.

The product of the roots must be -10, eliminating choice 'a'. Thus, the only viable choice is C.

_____

The product of the roots of C is ...

(15 -√235)(15 +√235) = 15² -235 = -10 . . . . as required

User ProfoundWanderer
by
4.8k points