How many x-intercepts does the graph of y = 2x^2 – 8x + 5 have?
2 answers:
A graph of the equation shows the appropriate choice to be
C. 2
_____
If you would rather, you can look at the value of the discriminant. For the equation y = ax²+bx+c, the discriminant (d) is
d = b²-4ac
For your equation, this evaluates to
d = (-8)²-4(2)(5) = 64 -40 = 24
When the discriminant is positive, the function has two real roots (2 x-intercepts). When it is zero, there is only one x-intercept, and when it is negative, there are none (the roots are complex).
C. 2
_____
If you would rather, you can look at the value of the discriminant. For the equation y = ax²+bx+c, the discriminant (d) is
d = b²-4ac
For your equation, this evaluates to
d = (-8)²-4(2)(5) = 64 -40 = 24
When the discriminant is positive, the function has two real roots (2 x-intercepts). When it is zero, there is only one x-intercept, and when it is negative, there are none (the roots are complex).
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Answer:
Answer of 17 is ㏒(+15x), Answer of 33 is x = 8 , Answer of 35 is x = ㏒10/㏒2 , Answer of 37 is x = -㏒12/㏒8 and Answer of 39 is x = 5
Step-by-step explanation:
17. ㏒x + ㏒(x+15)
Using property ㏒a + ㏒b = ㏒a×b
∴ ㏒x + ㏒(x+15)
㏒x×(x+15)
㏒(+15x)
The answer is ㏒(+15x)
33. 2^(x-5) = 8
2^(x-5) = 2^3
Using property 2^a = 2^b
Then a = b
∴x-5 = 3
x = 8
The answer is x = 8
35. 2^x = 10
Taking log on both sides gives
㏒2^x = ㏒10
x×㏒2 = ㏒10
x = ㏒10/㏒2
The answer is x = ㏒10/㏒2
37. 8^-x = 12
Taking log on both sides gives
㏒8^-x = ㏒12
-x×㏒8 = ㏒12
x = -㏒12/㏒8
The answer is x = -㏒12/㏒8
39. 5(2^3 × x) = 8
5(8×x) = 8
x = 5
The answer is x=5