Question

Solve x2 – 8x + 15 < 0. Select the critical points for the inequality shown.

Answer 1

Answer:

x=3,5

Explanation:

x2−8x+15=0

Try to express the terms of the equation in square form.

Adding 16 both sides of the equation,

(x2−2⋅x⋅4+42)+15=16

or,(x−4)2+15−16=0

or,(x−4)2−1=0

or,(x−4)2−12=0

This is the a2−b2=(a+b)(a−b)form.

(x−4+1)(x−4−1)=0

or,(x−3)(x−5)=0

Now, equate both the terms to zero since both of them when multiplied, give zero.

Either,

x−3=0

∴x=3

Or,

x−5=0

∴x=5

Ans:x=3,5 Hope this helpsXD...!!

Answer 2

Answer:

3<x<5

Step-by-step explanation:

an Univariate quadratic polynomial can be divided into the product of two first order equations

In this example, x2 - 8x + 15 =  (x-3) * (x-5) <0

as a result. the answer is 3< x <5