Step-by-step explanation:
4x2=−9x−4
Step 1: Subtract -9x-4 from both sides.
4x2−(−9x−4)=−9x−4−(−9x−4)
4x2+9x+4=0
For this equation: a=4, b=9, c=4
4x2+9x+4=0
Step 2: Use quadratic formula with a=4, b=9, c=4.
x=
−b±√b2−4ac
2a
x=
−(9)±√(9)2−4(4)(4)
2(4)
x=
−9±√17
8
x=
−9
8
+
1
8
√17 or x=
−9
8
+
−1
8
√17
Answer
D
Hope this help you?
sorry i just want some points :)
Questions (contd)
(a) For what amount of driving do the two plans cost the same?
(b) What is the cost when the two plans cost the same?
Answer:
(a) 100 miles
(b) $65
Step-by-step explanation:
Given
Plan 1:
per mile
Plan 2:
per mile
Solving (a): Number of miles when both plans are equal
Represent the distance with x and the cost with y
So:
Plan 1:
Plan 2:
To solve (a), we equate both plans together; i.e.
Collect Like Terms
Solve for x
Hence, 100 mile would cost both plans the same
Solving (b): Cost when both plans are the same:
In this case, we simply substitute 100 for x in any of the y equation.
<em>Hence, the amount is $65</em>
Subtract the y then add the 4 to the other side so y=0