Need help with Method 1/2 questions

[JamesCheng69]

Hi there!

Would anyone be able to assist me with these three multiple choice questions? I have absolute no idea how to do those and there's nothing on the method textbook to explain how.

Thanks!

[1729]

Hi there!

Would anyone be able to assist me with these three multiple choice questions? I have absolute no idea how to do those and there's nothing on the method textbook to explain how.

Thanks!

For question 12 use discriminant which is b^2 - 4ac. Sub the values u have, a=1, b=-t and c=t, so (-t)^2-4*1*t which is t^2 - 4t.

For when there is one solution discrim is 0, so t^2 - 4t = 0, t(t-4)=0 so therefore t=4. Now we sub that into the original equation to get x^2 - 4t + 4=0, that is (x-2)^2=0 and we know x has to be more than 0 so therefore x=2.

For question 13 use quadratic formula (rearrange equation to get 5x^2-4x-t) and sub in for a=5, b=-4, c=-t.

For question 14 cross multiply through,

Which gets you