Question

3. Solve the equation using square roots. If the equation has no real solution, write

Answer 1

3) x² - 121 = 0

x² = 121

x' = +√121

x' = 11

_______________

x'' = - √121

x'' = -11

Solution ⇒ S{-11 ; 11 } or (x-11)(x+11)

4) 4x² + 144 = 0

4x² = -144

x² = -144 / 4

x² = -36

x = √-36

No solution ⇒ S = ∅

5) z²+10z+21 = 0

Δ = 10² - 4(1)(21)

Δ = 100 - 84

Δ = 16

x' = (-10+4) / 2 = -6/2 = -3

x'' = (-10-4) / 2 = -14/2 = -7

Solution ⇒ S{ -7 ; -3} or (x+3)(x+7)