Answer:
x = ± 2[tex]\sqrt{5}[/tex]
Step-by-step explanation:
Given
x² = 20 ( take the square root of both sides )
x = ± [tex]\sqrt{20}[/tex] = ± [tex]\sqrt{4(5)}[/tex] = ± 2[tex]\sqrt{5}[/tex]
Answer:
Step-by-step explanation:
x² = 20
x² - 20 = 0
x² - (√20)² =0
by identity : a² - b² = ( a - b )( a + b) in this exercice : a = x and b =√20
( x - √20)(x + √20) = 0
x - √20 = 0 or x + √20 = 0
x = √20 or x = - √20
but : 20 = 4×5
20 = √(4×5) =√4×√5 = 2√5
