Answer:
x = -3, 6
Step-by-step explanation:
First, add 18 to both sides
x² - 3x - 18 = 0
+ 18 + 18
x² - 3x = 18
Add 9/4 to both sides because that is the square of half of -3
x² - 3x + 9/4 = 18 + 9/4
Multiply both sides by 4 to get rid of the fractions
(x² - 3x + 9/4 = 18 + 9/4)4
4x² - 12x + 9 = 72 + 9 = 81
Factor the left side of the equation
(2x - 3)² = 81
√(2x - 3)² = √81
Because of the square root, this will result in a positive number and a negative number
2x - 3 = 9
2x - 3 = -9
For both equations, add 3 to both sides then divide by 2
2x - 3 = 9
+ 3 +3
2x = 12
2x/2 = 12/2
x = 6
2x - 3 = -9
+ 3 + 3
2x = -6
x = -3
Step-by-step explanation:
when multiplied together, the gradients of the 2 graphs should equal -1 (of they are perpendicular).
x-7y=4
-7y= -x + 4
y= -1/7 x + 4/7
21x+ 3y=11
3y=-21x+11
y=-21/3 x + 11/3
-21/3 * -1/7 = 1
when multipled together, the 2 gradients dont equal -1 therefore they are not perpendicular
unless I've made a mistake with the signs at some point haha
Answer:
Step-by-step explanation:
Given
tan x = 
, then
x = 
( ) = 60° ← related acute angle
Since 180° < x < 270° and tan x > 0 then x is in third quadrant
x = 180° + 60° = 240°
and
sin(x - 210)°
= sin(240 - 210)°
= sin30°
=
Answer:
8.55 inches tall
Step-by-step explanation:
equation: h = -0.75t +12. The slope is -0.75 because that's the rate of the candle burning, and the y intercept is 12 because that's how tall it is initially.
Now plug in 4.6 for t you get:
h = -0.75t + 12
h = -0.75(4.6) + 12
h = -3.45 +12
h = 8.55 inches tall
Answer:
<em>An </em><em>echo</em>
Step-by-step explanation:
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