(i) (-1) × a = -a
(ii) (-1) × 0 = 0 [∵ a × 0 = 0] Hence (c) 0 is the required integer.
i) For any integer a, multiplying by −1 results in the negation of a:
\((-1) \times a = -a \quad (\text{where } a \text{ is any integer})\)
ii) Solve the following equations to find the required integer a:
(a) \( ?×(−1)=−22\)
Let a be the required integer:
\(a \times (-1) = -22\)
\(−a=−22\)
\(a=22\)
Substituting a back into the equation:
\(22 \times (-1) = -22\)
Thus, the required integer is 22.
(b)\(? \times (-1) = 37\)
Let a be the required integer:
\(a \times (-1) = 37\)
\(−a=37\)
\(a=−37\)
Substituting a back into the equation:
\(-37 \times (-1) = 37\)
Thus, the required integer is -37.
(c) \( ? \times (-1) = 0\)
Let a be the required integer:
\(a \times (-1) = 0\)
\(−a=0\)
\(a=0\)
Substituting a back into the equation:
\(0 \times (-1) = 0\)
Multiplying any number by 0 results in 0.
Thus, the required integer is 0.
Match the items given in Column I with one or more items of Column II.
Column I | Column II |
(a) A plane mirror | (i) Used as a magnifying glass. |
(b) A convex mirror | (ii) Can form image of objects spread over a large area. |
(c) A convex lens | (iii) Used by dentists to see enlarged image of teeth. |
(d) A concave mirror | (iv) The image is always inverted and magnified. |
(e) A concave lens | (v) The image is erect and of the same size as the object. |
- | (vi) The image is erect and smaller in size than the object. |