] Circle the statements below that are true for all values of x, y, and z. For any statement that is not always true, give an example of values of x, y, and z for which the statement is not true. (a) x(yz) = (xy)z. (b) x ÷ (y ÷ z) = (x ÷ y) ÷ z. (c) x + (y + z) = (x + y) + z. (d) x − (y − z) = (x − y) − z.

answer: i think it is (1,-2)

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15