Answer:
Step-by-step explanation:
21) x² - 4x - 5 > 0
x² - x + 5x - 5 > 0
x(x - 1) + 5(x - 1) > 0
(x - 1) (x + 5) > 0
x - 1 >0 or x + 5 > 0
x > 1 or x > - 5 Ans: D
22) 4p² ≤ 1
p² ≤ 1/4
p ≤ 1/2 or p ≥ -1/2
-1/2 ≥ p ≤ 1/2
23)y < 3x² + 3x - 6
(1 , -7)
x = 1 and y = -7
-7 < 3*1 + 3*1 - 6
-7 < 3 + 3 - 6
-7 < 0
(1 , -7) satisfies the equation.
Option b
24) 5x² - 7x = 0
a = 5 ; b = -7 ;c = 0
Discriminant = b² - 4ac = 49 - 0 = 0
[tex]x = \dfrac{-b+\sqrt{D}}{2a} \ ; \ \dfrac{-b-\sqrt{D}}{2a}\\\\x = \dfrac{7+\sqrt{49}}{10} ; \dfrac{7-\sqrt{49}}{10}\\\\x = \dfrac{7+7}{10};\dfrac{7-7}{10}\\\\x =\dfrac{14}{10} ; 0\\\\x = \dfrac{7}{5}; 0[/tex]
x = 0 ; x = 7/5 Option a)
25) m² - 11 m + 18 = 0
m² - 2m - 9m + (-9)*(-2) = 0
m(m - 2) - 9(m - 2) = 0
(m - 2)(m - 9) = 0
m = 2 , 9
x = 2 and y =9
x² + y² = 2² + 9² = 4 + 81 = 85 Option a)
26) x² - 2x - 1 = 0
Add the constant 1 to both sides
x² - 2x = 1
Divide the coefficient of x by 2. 2/2 = 1. Now add this 1 to both sides of the equation.
x² - 2x + 1 = 1+1
x² - 2x + 1 = 2
(x - 1)² = 2
Take square root
x - 1 = ±√2
x = 1 ± √2 Option a)
