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Published on: 03/09/2019
Simple Equations
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Questions + Answers key
Take MCQ Mathematics Test

1.
Write the following equations in statement form.
m - 7 = 3.
2.
Check whether the value given in the brackets is a solution to the given equation or not: 7n+5 = 19(n=2)
3.
Solve the equation 6x- 4= 22.
4.
Solve the following: Laxmi's father is 49 yr old. He is 4 yr older than three times Laxmi's age. What is Laxmi's age?
5.
Set up equation and solve them to find the unknown numbers in the following cases. If I take three-fourths of a number and add 3 to it, I get 21.
6.
Solve the following equation by trial and error method. 5p+2 =17
7.
The age of Sohan Lal is four times that of his son Amit. If the difference of their ages is 27 yr, find the age of Amit.
8.
Which of the following numbers satisfies the equation -6 + x = -18?
10
-13
-12
-16
9.
The equation having -3 as a solution is
x + 3 = 1
8 + 2x = 3
10 + 3x = 1
2x + 1 = 3
10.
If k + 7 = 16, then the value of 8k - 72 is equal to
0
1
112
56
11.
The solution of the equation mx + n = 0 is
\(\frac{-n}{m}\)
\(\frac{n}{m}\)
\(\frac{2n}{m}\)
\(\frac{m}{n}\)
12.
If \(x-\frac{1}{2}=\frac{-1}{2}\) then x = _________.
13.
Any term of an equation may be transposed from one side of the equation to the other side of the equation by changing the ___________ of term.
14.
x - ________ = 15, when \(\frac{x}{2}=6\)
15.
One-third of a number when added to itself, gives 10, then it can be represented as \(\frac{x}{3}+10=x\)
16.
If 2(k + 1) = 19, then the value of 6k - 3 is 32.
17.
If \(x-\frac{7}{8}=\frac{7}{8}\) then \(x=\frac{7}{4}\)
1.
The given equations in statement form are as follows:
The difference of m and 7 is 3.
2.
When, n = 2
then 7n + 5 = 7 \(\times\) 2 + 5 = 14 + 5
= 19
So, n = 2 is the solution of the given equation.
3.
Given equation, 6x - 4 = 22
We will try to get x on LHS of this equation
∴ 6x - 4 + 4 = 22 + 4 ⇒ 6 x= 26 [adding 4 to both sides]
Now, on dividing both sides by 6, we get
\(\frac { 6x }{ 6 } =\frac { 26 }{ 6 } \) or \(x=\frac { 26 }{ 6 } =\frac { 13 }{ 3 } \) [dividing numerator and denominator by 2]
Thus, x =\(\frac { 13 }{ 3 } \) is the solution.
4.
Let Laxmi 's age be x yr, then 4 times of Laxrni's age be 4x.
\(\therefore\) Laxmi's father age = 3x + 4, but Laxmi's father is 49 yr.
Therefore, we get the equation, 3x + 4 = 49
To solve this equation, transposing 4 from LHS to RHS, we get 3x = 49 - 4 \(\Rightarrow\) 3x = 45
On dividing both sides by 3, we get = 15
Hence, Laxmi's age is 15 yr.
5.
Let the number be x.
Three-fourths of the number = \(\frac{3}{4}x\)
According to the question,
On adding 3 to it, we get 2l.
i.e. \(\frac{3}{4}x+3=21\)
which is the required equation.
Now, to solve this equation, transposing (+3) from LHS to RHS, we get
\(\frac{3}{4}x=21-3\quad \Rightarrow \frac{3}{4}x=18\)
On multiplying both sides by 4, we get
\(\frac{3}{4}x\times 4=18\times 4\Rightarrow 3x=72\)
Again, dividing both sides by 3, we get
\(\frac{3x}{3}=\frac{72}{3}\quad \Rightarrow x=24\)
Hence, the required number is 24.
6.
Given equation is 5P + 2 = 17.
When P = 0, then LHS = 5\(\times\)0 + 2 = 0 + 2 = 2
and RHS = 17
∴ LHS ≠ RHS
When p = 1, then LHS = 5\(\times\)1+ 2 = 5 + 2 = 7
and RHS = 17
∴ LHS ≠ RHS
When p = 2, then LHS = 5\(\times\)2 + 2 = 10 + 2 = 12
and RHS =17
∴ LHS ≠ RHS
When p = 3, then LHS = 5\(\times\)3 + 2 = 15 + 2 = 17
∴ LHS = RHS
So, p = 3 is the solution of the given equation.
7.
Let x be the age of Amit.
So, age of Sohan Lal, the father of Amit = 4x yr
If the difference of their ages is 27 yr.
Then, 4x- x = 27 \(\Rightarrow\) 3x = 27 \(\Rightarrow x=\frac{27}{3}=9\)
Hence, age of Amit is 9 yr.
8.
(c)
-12
9.
(c)
10 + 3x = 1
10.
(a)
0
11.
(a)
\(\frac{-n}{m}\)
12.
Given, \(x-\frac{1}{2}=\frac{-1}{2}\)
\(\frac{2x-1}{2}=\frac{1}{2}\Rightarrow \) 2x - 1 = -1 \(\Rightarrow\) 2x = 0 \(\Rightarrow\) x = 0
So, if \(x-\frac{1}{2}=\frac{-1}{2}\) then x = 0.
13.
Any term of an equation may be transposed from one side of the equation to the other side of the equation by changing the sign of the term,
e.g. 2x + 4 = 2
If 4 is transposed. then
2x = 2 - 4 [sign changed]
14.
Given \(\frac{x}{2}=6 \Rightarrow\) = x = 6 x 2 = 12
\(\therefore\) 12 - (-3) = 12 + 3 = 15
So, x - (-3) = 15, When \(\frac{x}{2}=6\)
15.
(b)
16.
(b)
17.
(a)
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