17.1 N
11.4 N
36.5 N
5.7 N
Correct answer is B
m=4.56kg;t=16s;v1=(10ms−1,060o);v2=(50ms−1,060o)
Notice that there is no change in the direction of the velocity
So,we don't need to write it in a vector form
a=\frac{∆v}{t}=\frac{50 - 10}{16}
a=\frac{40}{16}=2.5ms^{-2}
F = ma = 4.56 x 2.5
∴ F = 11.4 N
Given that \frac{3x + 4}{(x - 2)(x + 3)}≡\frac{P}{x + 3}+\frac{Q}{x - 2},find the value of Q
2
-2
1
-1
Correct answer is A
\frac{3x + 4}{(x - 2)(x + 3)}≡\frac{P}{x + 3}+\frac{Q}{x - 2}
\frac{3x + 4}{(x - 2)(x + 3)}=\frac{P(x-2)+Q(x+3)}{(x-2)(x+3)}
=3x+4=P(x-2)+Q(x+3)
=3x+4=Px-2P+Qx+3Q
=3x+4=Px+Qx-2P+3Q
=3x+4=(P+Q)x-2P+3Q
Equating x and the constants
P+Q=3------(i)
2P+3Q=4-------(ii)
From equation (i)
P=3-Q------(iii)
Substitute (3-Q) for P inequation (ii)
=-2(3-Q)+3Q=4
=-6+2Q+3Q=4
=-6+5Q=4
=5Q=4+6
=5Q=10
∴Q=\frac{10}{5}=2
If 3x^2 + p x + 12 = 0 has equal roots, find the values of p .
±12
±3
±4
±6
Correct answer is A
The general form of a quadratic equation is:
x^2-(sum of roots) = 0
For equal roots it's:x^2 - 2(α)+(α)^2=0
3x^2+px+12=0
Divide through by 3
= x^2+\frac{p}{3}x+4=0
=x^2-(-\frac{p}{3})x+4=0
So,α^2=4
= α = √4 = ±2
Also,-\frac{p}{3}= 2α
When α = 2
-\frac{p}{3} = 2(2)=4
=p=-12
When α =-2
-\frac{p}{3}=2(-2)=-4
= p = 12
∴ values of p = ±12
If α and β are the roots of 7x2 +12x - 4 = 0,find the value of \frac{αβ}{(α + β)^2}
\frac{7}{36}
- \frac{36}{7}
\frac{36}{7}
- \frac{7}{36}
Correct answer is D
The general form of a quadratic equation is:
x^2 -(sum of roots)x +(product of roots) = 0
7x^2+12x-4=0
Divide through by 7
=x^2+\frac{12}{7}x-\frac{4}{7}=0
=x^2-(-\frac{12}{7})x+(-\frac{4}{7})=0
\therefore sum of roots = -\frac{12}{7}, and products of roots =-\frac{4}{7}
α + β = -\frac{12}{7}, αβ = -\frac{4}{7}
\frac{αβ}{(α + β)^2} = \frac{\frac{-4}{7}}{(\frac{-12}{7})^2}
=\frac{\frac{-4}{7}}{\frac{144}{49}}=-\frac{4}{7}\times\frac{49}{144}
\therefore - \frac{7}{36}
8(2x + 1)^2 + k
6(2x + 1)^2 + k
\frac{1}{8} (2x + 1)^4 + k
\frac{1}{6} (2x + 1)^4 + k
Correct answer is C
Using substitution method, Let u = 2x + 1
\frac{du}{dx}=2==>du=2dx==>dx=\frac{du}{2}
=\int\frac{u^3}{2} du = \frac{1}{2}\int u^3 du
=\frac{1}{2}(\frac{u^4}{4})=\frac{u^4}{8}
\therefore\frac{1}{8} (2x + 1)^4 + k