NCERT Solution class 7 Mathematics EXERCISE- 1.3
EXERCISE- 1.3
Q1. Find each of the following products:
(a) 3x(-1)
SOLUTION:-
By the rule of Multiplication of integers ,
=3 x (-1)
= -3 ——[(+x-=-)]
(b) (-1) x 225
SOLUTIONS:-
By the rule of multiplication of integers,
= (-1)x225
= – 225 —-[(-x+=-)]
(c) (-21)x(-30)
SOLUTION:-
By the rule of multiplication of integers,
= (-21) x (-30)
= 630 —–[(-x-=+)]
(d) (-316) x (-1)
SOLUTION:-
By the rule of multiplication of integers,
= (-316) x(-1)
=316 ——[ (-x-=+)]
(e) (-15) x 0x (-18)
SOLUTION:-
By the rule of multiplication of integer ,
= (-15) x0 x(-18)
= 0
Any integer is multiplied with zero and the answer is zero itself
(f) (-12) x(-11) x(10)
SOLUTION:-
By the rule of multiplication of integer,
= (-12) x(-11) x(10)
First multiply the two numbers having the same sign
=132 x 10 —-[(-x-=+)]
= 1320
(g) 9 x (- 3) x(-6)
SOLUTION :-
By the rule of multiplication of integer
= 9x(-3) x(-6)
First multiply the two numbers having same sign
9 x 18 —-[(-x-=+)]
= 162
(h) (-18) x( -5) x(-4)
SOLUTIONS:-
By the rule of multiplication of integer
= (-18) x (-5) x( – 4 )
First multiply the two numbers having same sign
= 90 x (-4) —-[(-x-=+)]
= -360
(i) (-1) x(-2) x(-3)x 4
SOLUTION:-
By the rule of multiplication of integer
= [ (-1) x (-2) ]x[(-3) x4 ]
= 2x (-12)
= – 24
(j) (-3) x (-6) x(-2) x(-1)
SOLUTIONS:-
By rule of multiplication of integer
= [(-3) x(-6) ]x [(-2) x (- 1)]
First multiply the two numbers having same sign
= 18 x 2 —–[ (-x-=+)
= 36
Q2. Verify the following :
(a) 18 x [7+(-3)]=[18×7]+[18 x (-3)]
SOLUTION:-
From the given equation
Let us consider the Left Hand Side (LHS) first = 18 x [ 7 +(-3)]
= 18 x [ 7-3]
= 18 x4
= 72
Now consider the Right Hand Side (RHS) = [18 X 7 ] + [ 18 X (-3) ]
= [ 126]+ [-54]
= 126 – 54
= 72
By comparing LHS and RHS
72=72
Hence the given equation is verified
(b) (-21)x [(-4)+(-6) ]=[(-21)x(-4)]+[(-21)x(-6)]
SOLUTION:-
From the given equation
Let us consider the Left Hand Side (LHS)first = (-21)x[(-4)+(-6)]
= (-21)x [-4-6]
= (-21)x[-10]
= 210
Now consider the Right Hand Side (RHS) = [(-21) x (-4) ]=[(-21) x (-6) ]
= [84] + [126]
= 210
By comparing LHS and RHS
210=210
LHS=RHS
Hence the given equation is verified