Question

2x squared minus 1 equals 21​

Answer 1

x = √11

Step-by-step explanation

2x² - 1 = 21

negative sign crossing an equal to sign becomes a positive sign

2x² - 1 = 21 + 1

2x² = 22

x² = 22 / 2

x = √11

Answer 2

x = √11

Explanation:

2x² - 1 = 21

add 1 to both sides

2x² - 1 + 1 = 21 + 1

simplify

2x² = 22

x² = 22 / 2

x = √11