2009 - JAMB Mathematics Past Questions and Answers - page 7

Tn = (\frac{1}{2})n(2a + (n - 1)d)

= (\frac{1}{2})n(2 x 5 + (n - 1) 6

= (\frac{1}{2})n(10 + 6n - 6)

= n(\frac{1}{2})(6n + 4)

= n(3n + 2)

3x - 7 (\leq) 0 ; x + 5 > 0

3x (\leq) 7 ; x > -5

= x (\leq) (\frac{7}{3})

-5 < x (\leq) (\frac{7}{3})

If m x n = n

= n - (m + 2)

3 (\ast) (-5) = -5 - (3 + 2)

= -5 - 5

= -10

If Q = (\begin{pmatrix} 9 & -2 \ -7 & 4 \end{pmatrix}), then |Q| is

= 9 x 4 - (-2) x (-7)

= 36 - 14

= 22

If p = (\begin{pmatrix} x + 3 & x + 2 \ x + 1 & x - 1 \end{pmatrix}) evaluate x if |p| = -10

|P| = (x + 3)(x - 1) - (x + 2)(x + 1)

x² + 2x - 3 - (x² + 3x + 2)

x² + 2x - 3 - x² - 3x - 2

-x - 5 = -10

-x = -10 + 5

x = 5

x (\leq) 90^o (acute angle)

x² = 3x

3x = 90^o

x = (\frac{90^o}{3}) = 30^o

x + 150^o = 180^o (sum of angle on straight line)

x = 180^o - 150^o , x = 30^o

number of sides (n) = (\frac{360}{3})

= 12

sin45^o = (\frac{y}{2})

y = 2 sin45^o

y = 2 ((\frac{1}{\sqrt{2}}))

y = (\frac{2}{\sqrt{2}}) x (\frac{\sqrt{2}}{\sqrt{2}})

y = (\frac{2\sqrt{2}}{2})

y = (\sqrt{2})

Since it is an isosceles triangle

x = (\sqrt{2})

Area of (\Delta) = (\frac{1}{2})bh

= (\frac{1}{2}) x (\sqrt{2}) x (\sqrt{2})

= (\frac{1}{2}) x 2

= 1 cm²