We Distribute, Yet Things Multiply Class 8 MCQ

We Distribute, Yet Things Multiply Class 8 MCQ

We Distribute, Yet Things Multiply Class 8 MCQ

Question 1.

(x - 8) (3x- 4) is equal to

(a) 3x² - 20x + 32

(b) 3x² - 28x + 32

(c) 3x² - 24x - 32

(d) 3x² - 20x - 32

Answer:

(b) 3x² - 28x + 32

Question 2.

(a + b) (c - d) is equal to

(a) ac + bc - ad - bd

(b) ac - bc + ad - bd

(c) bc - ac - ad + bd

(d) bc - ac + ad - bd

Answer:

(a) ac + bc - ad - bd

Question 3.

(5 - y) (y - 7) is equal to

(a) 2y - y² - 35

(b) 12y - y² + 35

(c) 12y - y² - 35

(d) 2y - y² + 35

Answer:

(c) 12y - y² - 35

Question 4.

(a + 3) (b - 2) is equal to

(a) ab + 3a - 2b - 6

(b) ab - 2a + 3b + 6

(c) ab - 3a + 2b + 6

(d) ab - 2a + 3b - b

Answer:

(d) ab - 2a + 3b - b

Question 5.

(a + 2)(a + 8) - (a + 1) (a + 9) is equal to

(a) 6

(b) 7

(c) 8

(d) 9

Answer:

(b) 7

Case Study

Question 1.

Division and remainder A number leaves a remainder of 4 when divided by 7 and another number leaves a remainder of 5 when divided by 7.

(i) What is algebraic expression for the first number ?

(a) 7x - 4

(b) 7x + 4

(c) 4x + 1

(d) 4x - 7

(ii) What is algebraic expression for the second number ?

(a) 5x + 7

(b) 5x - 1

(c) 7x - 5

(d) 7x + 5

(iii) What will be the remainder, when the sum of these two numbers is divisible by 7?

(iv) What will be the remainder, when the difference of these two numbers is divided by 7?

(v) What will be the remainder, when the product of these two numbers is divided by 7?

Answer:

(i) (b)

(ii) (d)

(iii) 2

(iv) 6

(v) 6

Question 2.

Increasing and decreasing numbers

Two positive numbers a and b (a > b) are written on the blackboard. Their product is ab.

(i) If a is increased by 1 and b is increased by 1, then what will be the change in their product ?

(ii) If a is increased by 1 and b is decreased by 1, then what will be the change in their product ?

(iii) If a is decreased by 1 and b is increased by 2, then what will be the change in their product ?

(iv) If a is increased by 2 and 6 is increased by 2, then what will be the change in their product ?

(v) If a is increased by 2 and 6 is decreased by 2, then what will be the change in their product ?

Answer:

(i) Increased by a + b + 1

(ii) change by -a + b - 1

(iii) change by 2a - b - 2

(iv) change by 2a + 2b + 4

(v) change by -2a + 2b - 4.