Question

Solve x2 – 8x + 15 < 0.

Select the critical points for the inequality shown.

–15

–5

–3

3

5

Answer 1

Answer:

x=3,5

Step-by-step 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

x2 - 8x + 15 = 0
(x - 3)(x - 5) = 0
critical points are at 3 and 5