Find the constant term in the binomial expansion of (2x−3x)8.
90720
1296
1120
672
Correct answer is A
(x)n(x−1)8−n=x0
xn.x−8+n=x0⟹n−8+n=0
2n−8=0⟹n=4
Constant term = 8C4(24)(34)=70×16×81
= 90720
Find the values of x at the point of intersection of the curve y=x2+2x−3 and the lines y+x=1.
(1, -2)
(0, 4)
(2, -3)
(1, -4)
Correct answer is D
Equate the equation of the curve and the line in order to find their point of intersection ie The values of y in both equations.
y+x=1⟹y=1−x
x2+2x−3=1−x
x2+2x+x−3−1=0⟹x2+3x−4=0
(x−1)(x+4)=0
x=(1,−4)
If P(x - 3) + Q(x + 1) = 2x + 3, find the value of (P + Q).
0
1
2
3
Correct answer is C
No explanation has been provided for this answer.
A fair die is tossed twice. Find the probability of obtaining a 3 and a 5.
512
23
118
136
Correct answer is D
P(c and e) = P(c)×P(e)
P(3) = 16
P(5) = 16
P(3 and 5) = \frac{1}{6} \times \frac{1}{6} = \frac{1}{36}\)
Which of the following is nor a measure of central tendency?
Mean
Variance
Median
Mode
Correct answer is B
Variance is a measure of dispersion not central tendency.