Answer:
1st one
Step-by-step explanation:
=
−
2
±
1
0
√
3
Step-by-step explanation:
21. x² - 4x - 5 > 0
→ (x - 5) (x - 1) > 0
{x - 5 > 0
{x + 1 > 0
{x - 5 < 0
{x + 1 < 0
{x > 5
{x > -1
{x < 5
{x < -1
= x < -1 or x > 5
therefore, option A is correct
22). 4p² - 1 ≤ 0
(2p - 1) (2p + 1) ≤ 0
{2p - 1 ≤ 0
{2p + 1 ≥ 0
{2p - 1 ≥ 0
{2p + 1 ≤ 0
{p ≤ 1/2
{p ≥ -1/2
{p ≥ 1/2
{p ≤ -1/2
1/2 ≤ p ≤ 1/2
{p ≥ 1/2
{p ≤ -1/2
-1/2 ≤ p ≤ 1/2
therefore, option A is correct.
23). y < 3x² + 3x - 6
3x² + 3x - 6 = 0
3x² + 6x - 3x - 6 = 0
3x(x +2) - 3(x +2) = 0
(x +2) (3) (-3) = 0
x = -2, 1
this is the correct ans. but their is no option similar to it.
25. x and y are root of
m² - 11m + 18 = 0
hence, x + y = 11
xy = 18
2xy = 36
now, x² + y²
= (x +y)² - 2xy
= (11)² - 36
= 121 - 36
= 85
therefore, option A is correct.
26. x² - 2x - 120
(x -1)² - 1 - 1² = 0
(x -1)² = 1 + 1²
x - 1² = 2
x - 1 = ±√2
1 ± √2
therefore, option A is correct.
hope this answer helps you dear..take care!
80.51275. Because 1 pound=0.453592 kilograms. 0.453592*71=32.2051 32.2051*2.5=80.51275
Answer:
(x-12)(x+7)
Step-by-step explanation:
x^2 - 5x - 84
You find the factors of 84:
1,84; 2,42; 3,28; 4,21; 6,14; 7,12
7 and 12 are 5 apart, so we use them:
(x - 12)(x + 7)
The 12 is negative because it's greater than 7, and the coefficient of x is negative 5.
2.37
TO round it, first you look at the number on the right of the whole number. If its over 5, then you round it up. If its less than 5 than you round it down.
In this case its 3 <5
So your going to round it down.
So the answer would be 2.