The answer is (2,-9). Hope i can help.
Step-by-step explanation:
4x² - 12x + 9 = 5 → 4x² - 12x + 4 = 0 → x² - 3x + 1 = 0
∆ = b² - 4ac → ∆ = (-3)² -4(1)(1) = 9 - 4 = 5
x = (-(-3) ± √5)/2(1) = (3 ± √5)/2
x² - 3x + 1 = 0 → (x - 3/2)² - 9/4 + 1 = 0 → (x - 3/2)² = 5/4 → x - 3/2 = ±√5 / 2 → x = ½( 3 ± √5)
Answer:
(a)Therefore the value of x=
(b) Therefore the value of x 
Step-by-step explanation:
Horizontal tangent line: The first order derivative of a function gives the slope of the tangent of the function. The slope of horizontal line is zero.If the slope of tangent line is zero then the tangent line is called horizontal tangent line.
(a)
Given function is,

Differential with respect to x

For horizontal tangent line, f'(x)=0
3+ 3 cos x= 0
⇒3 cos x=-3
⇒cos x=-1
⇒x = 180° 
Therefore the value of x=
(b)
Given that, the slope is 3.
Then,f'(x)=3
3+ 3 cos x= 3
⇒3 cos x= 3-3
⇒cos x=0
⇒x = 90° 
Therefore the value of x 
Answer:
Her son is 10 years old.
Step-by-step explanation:
Let son be x
Ellie is 4x
In 5 years time: Her son = x + 5
Ellie = 4x + 5
Given that she will then be 3 times as old as her son: 4x + 5 = 3(x + 5)
Solve x: 4x + 5 = 3(x + 5) ,4x + 5 = 3x + 15
x = 10