(c) The line with equation y = 2x +k is a tangent to curve y = 3x² +4. Find the value of k.
1 answer:
Answer:
k = 11/3
Step-by-step explanation:
If the line is tangent to the curve, then Δ = 0.
______________
Remembering:
Δ>0 two different points of intersection x' x''
Δ=0 one point of intersection x' = x''
Δ<0 two different points of intersection in the complex plan x' and -x'
______________
As the line and the curve have one point of intersection, which is (x, y), we can make a equality between them:
2x + k = 3x² + 4
0 = 3x² - 2x + (4 - k)
Now we can use the Δ=0 (Δ= b² - 4ac)
Δ = 0 = (-2)² - 4.3.(4-k)
0 = 4 - 48 + 12k
12k = 44
k = 44/12 = 2 . 22 /3. 2.2 = 22/3.2 = 11/3
k = 11/3
You might be interested in
Answer:
w = 10 cm
Step-by-step explanation:
The area (A) of the triangle is calculated as
A = base × height
here base = 6 and height = 8, thus
A = 0.5 × 6 × 8 = 3 × 8 = 24 cm²
The area of the rectangle = 5 × 24 = 120 cm²
area of rectangle = lw ( l is length, w is width )
Here l = 12, thus
120 = 12w ( divide both sides by 12 )
w = 10 cm