Answer:

1. x² - 2x = 3

x² - 2x + 1 = 3 + 1

x² - 2x + 1 = 4

(x - 1)² = 4

x - 1 = √4

x - 1 = ± 2

x = 1 ± 2

x= 3 and x= -1

2. s² + 4s - 21 = 0

s² + 4s = 3

s² + 4s + 4 = 21 + 4

s² + 4s + 4 = 21 + 4

(s + 2)² = 25

s + 2 = √25

s + 2 = ± 5

s = -2 ± 5

s= 3 and s= -7

3. t² + 10t + 9 = 0

t² + 10x + 9= 0

t² + 10x + 25 = -9 + 25

t² + 10x + 25 = 16

(t + 5)² = 16

t + 5 = √16

t + 5 = ± 4

t = -5 ± 4

t= -1 and t= -9

Step-by-step explanation:

church: x= 3 and x= -1

1. (-1)² - 2(-1) = 3

-1² - 2(-1) = 3

-1² - 2(-1) + (-3) = 0

1 + 2 + (-3) = 0

3 - 3 = 0

0 = 0

0 ✓ 0

Check: s= 3 and s= -7

2. s² + 4s - 21 = 0

(3)² + 4(3) -21 = 0

9 + 12 - 21 = 0

21 - 21 = 0

0 = 0

0 ✓ 0

Check: t= -1 and t= -9

3. t² + 10t + 9 = 0

t² + 10x + 9= 0

(-1)² + 10(-1) + 9 = 0

1 + (-10) + 9 = 0

1 - 10 + 9 = 0

-9 + 9 = 0

0 = 0

0 ✓ 0