Gujarat BoardEnglish MediumSTD 7MATHSSimple Equations1 Mark
MCQ
The equation which cannot be solved in integers is:
A
$5y - 3 = - 18$
B
$3x - 9 = 0$
✓
$3z + 8 = 3 + z$
D
$9y + 8 = 4y - 7$
✓
Answer
Correct option: C.
$3z + 8 = 3 + z$
Let us solve the equation:
$a.$ Given equation is $5y - 3 = -18$
$\Rightarrow5\text{y}=-18+3[ $transposing $3$ to $\text{RHS}]$
$\Rightarrow5\text{y}=-15$
$\Rightarrow\text{y}=-3 ($integer$) [$dividing both sides by $5]$
$b.$ Given equation is $3z - 9 = 0$
$\Rightarrow3\text{x}=9 [$transposing $9$ to $\text{RHS}]$
$\Rightarrow\text{x}=3( $integer$) [$dividing both sides by $3]$
$c.$ Given equation is $3z + 8 = 3 + z$
On transposing $z$ and $8$ to $\text{LHS}$ and $\text{RHS}$ respectively, we get
$\Rightarrow3\text{z}-\text{z}=3-8$
$\Rightarrow2\text{z}=-5$
$\Rightarrow\text{z}=-\frac{5}{2}[$dividing both sides by $2]$
Which is neither a positive fraction nor an integer.
$d.$ Given equation is $9y + 8 = 4y - 7$
On transposing $4y$ and $8$ to $\text{LHS}$ and $\text{RHS}$ respectively, we get
$\Rightarrow9\text{y}-4\text{y}=-7-8$
$5\text{y}=-15$
$\Rightarrow\frac{5\text{y}}{5}=-\frac{15}{5}[$dividing both sides by $5]$
$\Rightarrow\text{y}=-3 ($integer$)$
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