1.1.3 Proof by contradiction (A-level only)

i.

Use proof by contradiction to show that for all $\in \mathbb{R}$

x^4 + 100 \ge 20x^2

[3]

ii.

Show that the following statement is not true.

"The sum of three consecutive even integers is always a multiple of 12."

[2]

i.

Use proof by contradiction to show that for all $\in \mathbb{R}$

x^4 + 100 \ge 20x^2

[3]

ii.

Show that the following statement is not true.

"The sum of three consecutive even integers is always a multiple of 12."

[2]

1.1.3 Proof by contradiction (A-level only) Questions