4. Rational, irrational (4 points) (1) (2 points) Prove or disprove that if x y is an irrational number, then x or y is also an irrational number. (2) (2 points) Prove that if x 2 is irrational, then x is irrational. (Hint: try a proof by contrapositive)

See explanation below

Step-by-step explanation:

1) Prove or disprove that if is an irrational number, then x or y is also an irrational number.

Let's take the following instances:

i) When x= 2 and y= we have:

ii) When and y=3, we have:

iii) When and , we have:

It is proven because, in scenario

i) x is rational and y is irrational

ii) x is irrational and y is rational

iii) x and y are irrational

2) Prove tha x² is irrational, then x is irrational.

Use contradiction here.

Thus, x² is irrational and x is rational.

when x is rational, a & b are integers.

Therefore, . This x² is rational.

This contradicts the statement that x² is irrational.

Therefore, if x² is irrational, x is also irrational.

f(2x−x2)=−3x2+6x−1

step-by-step explanation:

set up the composite function and evaluate.

f(2x−x2)=−3x2+6x−1