29JUL21

(x/3) + (4/5) = 1/4

x/3 = (1/4) - (4/5)

[While performing addition or subtraction on fractions, the key is to make the denominators the same.]

x/3 = (5/20) - (16/20)

x/3 = -11/20

x = (-11/20) * 3

x= -33/20


F+F+F=15

3F=15

F=15/3=5

R-4(F)=-5

R-4(5)=-5

R-20=-5

R=-5+20

[5 steps left, 20 steps right]

R=15


Bob's Age = x

Matt's Age = x+4

Lana's Age = 2(x+4)-5

=2x+2*4-5

=2x+8-5

=2x+3


Multiplication is distributive over addition.

a(b+c) = ab+ac

This is known as DISTRIBUTIVE PROPERTY.


(2/3)(5+3x-11)

=(2/3)*5 + (2/3)*3x - (2/3)*11

=(10/3) + 2x - (22/3)

=2x-(12/3)

=2x-4


Let's say length is l and breadth is b.

Perimeter = 2l + 2b

Area = lb

Perimeter is equal to thrice the area.

2l+2b = 3lb

b=1 cm

2l+2*1 = 3l*1

2l+2=3l

3l=2l+2

3l-2l=2

l=2 cm


-9-8

9 steps left, again 8 steps left

-17


No. of questions faced=20

Let's say, x answers were correct and y answers were wrong.

x+y=20..............(1)

For x correct answers, he gets 5x points, and, for y wrong answers, he gets -3y points.

5x-3y=20..............(2)

Multiplying (1) by 3,

3x+3y=60

5x-3y=20

Adding the two equations,

8x=80

x=80/8=10

y=20-x=20-10=10

[He gave 10 right answers, got 50 points, gave 10 wrong answers, lost 30 points.]



Comments

Post a Comment

Popular posts from this blog

17JUL21

Ax+By+C=0 Does this represent a straight line? Yes, it does because it is a "LINEAR" equation in x and y. (The power of x is 1 and the power of y is 1.) What is the slope of this line? What is the y-intercept of this line? And what is the x-intercept? By = -Ax-C y = (-Ax-C)/B y = (-Ax/B) - (C/B) y = (-A/B)x - (C/B) Compare this to y = mx+c m = -A/B c = C/B Therefore, Ax+By+C=0 has a slope of -A/B. Its y-intercept is -C/B. It cuts the Y-Axis at the point (0, -C/B). To find the x-intercept, we have to substitute 0 for y. Ax+By+C=0 Ax+B(0)+C=0 Ax+C=0 Ax=-C x = -C/A So the x-intercept is -C/A. That is, Ax+By+C=0 cuts the X-Axis at the point (-C/A,0). Summary: Ax+By+C=0, Slope=-A/B, y-intercept=-C/B, x-intercept=-C/A What is the slope of any line parallel to Ax+By+C=0? -A/B What is the slope of any line perpendicular to Ax+By+C=0? Let us say the slope of the perpendicular line is p. (-A/B)p=-1 p=(-1)(-B/A) p=B/A Analyse 2x+3y+4=0. [Comparing with Ax+By+C=0, A=2, B=3 and C=4.] 01) ...
Read more

13JUL21

Given the equation of a line, to find its slope, compare the given equation to y=mx+c. Whatever is the coefficient of x, it is the slope of the line. In the given equation, if the LHS is not y, you have to modify the given equation and bring it into the form y=mx+c. Given the equation of a line, to find its y-intercept, compare the given equation to y=mx+c. Whatever is the constant term, it is the y-intercept made by the line. Alternatively, we can substitute 0 for x, because any point on the Y-Axis will have its x-coordinate as zero. Given the equation of a line, to find its x-intercept, we can substitute 0 for y, because any point on the X-Axis will have its y-coordinate as zero. y=mx+c is called the slope-intercept form of a straight line. +a in the LHS becomes –a in the RHS. –a in the LHS becomes +a in the RHS. *a in the LHS becomes /a in the RHS. /a in the LHS becomes *a in the RHS.
Read more

20JUL21

What is the slope of (x/2) + (y/3) = 1? 3/2 Does this line make an acute angle with the X-Axis or obtuse? Obtuse Does the point (1,3/2) lie on this line? (x/2)+(y/3)=1 (1/2)+(3/2 divided by 3)=1 (1/2)+(1/2)=1 1=1 LHS=RHS Yes, the point lies on the line.
Read more