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PLEASE HELP ME

How many and what type of solution(s) does the equation have?
4p^2=12p-5

A. 1 rational solution
B. 2 irrational solutions
C. 2 non-real solutions
D. 2 rational solutions

User Reza Sam
by
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1 Answer

5 votes

Answer:

D. 2 rational solutions

Explanation:

You can answer this question by (a) solving the equation, or (b) evaluating the discriminant.

In the latter case, ...

4p^2 -12p +5 = 0 . . . . . . a=4, b=-12, c=5

The discriminant is ...

b^2 -4ac = (-12)^2 -(4)(4)(5) = 64

This is a perfect square, so the roots are real and rational, choice D.

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Once you get the quadratic in the standard form above, you can see that the factors will be related to the factors of 20 that sum to -12. As soon as you find these integer factors of 20, you know the roots are rational.

4p^2 -10p -2p +5 = 0 . . . . . . rewrite -12p using the factors -10 and -2

2p(2p -5) -1(2p -5) = 0 . . . . . .factor by grouping

(2p -1)(2p -5) = 0

The solutions are the values of p that make the factors zero, 1/2 and 5/2. Both are rational numbers.

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A graphing calculator shows you very quickly that the two roots are rational.

PLEASE HELP ME How many and what type of solution(s) does the equation have? 4p^2=12p-example-1
User Mczepiel
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