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JAMB Mathematics Past Questions & Answers - Page 144

716.

Evaluate without using tables sin(-1290º)

A.

32

B.

-32

C.

22

D.

1

E.

12

Correct answer is E

sin(-1290º) = -sin(1290º)

sin([3*360] + 210)

where sin 360 = 0 and sin 210 = 180 + 30 ⇔ -30º

-sin ([3* 0] + [-30]) 

-sin(-30)

sin30 = 12

717.

If x4 - kx3 + 10x2 + 1x - 3 is divisible by (x - 1), and if when it is divided by (x + 2) the remainder is 27, find the constants k and 1

A.

k = -7, 1 = -15

B.

k = -15, 1 = -7

C.

k = 153 , 1 = -7

D.

k = 73 , 1 = -17

Correct answer is A

If k = -7 is put as -15, the equation x4 - kx3 + 10x2 + 1x - 3 becomes x4 - (7x3) + 10x2 + (15)-3 = x4 + 7x3 + 10x2 - 15x - 3

This equation is divisible by (x - 1) and (x + 2) with the remainder as 27

k = -7, 1 = -15

718.

Simplify (a21a)(a43+a23)a21a2

A.

a23

B.

a-13

C.

a2 + 1

D.

a

E.

a13

Correct answer is E

(a21a)(a43+a23)a21a2

= (a21a)(a2+1a23)a41a2

= a41a53 x a2a41

= a13

719.

Without using tables, simplify 1n2161n1251n82(1n31n5)

A.

-3

B.

3

C.

35

D.

32

E.

1n 6 - 2 1n 5

Correct answer is C

No explanation has been provided for this answer.

720.

The locus of all points having a distance of 1 unit from each of the two fixed points a and b is

A.

A line parallel to the line ab

B.

A line perpendicular to the line ab through the mid-point of ab

C.

A circle through a and b with centre at the mid-point of ab

D.

A circle with centre at a and passes through b

E.

A circle in a plane perpendicular to ab and centre at the mid-point of the line ab

Correct answer is B

The locus of all points having a distance of 1 unit from each of the two fixed points. a and b is: a perpendicular to the (ab) through the mid-points ab