Question 76:

• WAEC 2017

If \(x^{2} - kx + 9 = 0\) has equal roots, find the values of k.

A. 3, 4
B. \(\pm3\)
C. \(\pm5\)
D. \(\pm6\)

Question 77:

• WAEC 2017

Find the coordinates of the centre of the circle \(3x^{2}+3y^{2} - 4x + 8y -2=0\)

A. (-2,4)
B. (\(\frac{-2}{3}, \frac{4}{3}\))
C. (\(\frac{2}{3}, \frac{-4}{3}\))
D. (2, -4)

Question 78:

• WAEC 2016

A ball falls from a height of 18m above the ground. Find the speed with which the ball hits the ground. \([g = 10ms^{-2}]\)

A. 9\(ms^{-1}\)
B. 9.49\(ms^{-1}\)
C. 13.42\(ms^{-1}\)
D. 18.97\(ms^{-1}\)

Question 79:

• WAEC 2016

A man of mass 80kg stands in a lift. If the lift moves upwards with acceleration 0.5\(ms^{-2}\), calculate the reaction from the floor of the lift on the man. \([g = 10ms^{-2}]\)

A. 760N
B. 800N
C. 805N
D. 840N

Question 80:

• WAEC 2016

A force 10N acts in the direction 060° and another force 6N acts in the direction 330°. Find the y component of their resultant force.

A. \((3 + 3\sqrt{3})N\)
B. \((-3 + 5\sqrt{3})N\)
C. \((5 + 3\sqrt{3})N\)
D. \((5 + 5\sqrt{3})N\)