SAT Mathematics Practice Test 2

Question : 27 of 58

Marks: +1, -0

y=x^2-6x+8

The equation above represents a parabola in the

xy-

plane. Which of the following equivalent forms of the equation displays the

x-

intercepts of the parabola as constants or coefficients?

$y-8=x^2-6x$
$y+1=(x-3)^2$
$y=x(x-6)+8$
$y=(x-2)(x-4)$

Validate

Solution:

The x-intercepts of the parabola represented by

y=x^2-6x+8

in the xy-plane are the values of x for which y is equal to

0

.The factored form of the equation,

y=(x−2)(x−4)

,shows that y equals

0

if and only if

x=2

x=4

. Thus, the factored form,

y=(x−2)(x−4),

displays the

x-

intercepts of the parabola as the constants 2 and 4.
Choices A, B, and C are incorrect because none of these $$forms shows the x-intercepts 2 and 4 as constants or coefficients.

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