8. Algebra Example 3:


a = 2, b = 3, find a value for: (i) a + b (ii) 2a + b (iii) a2


= 2 + 3 = 5 + b =22


= 2(2) + 3 = 4 + 3 = 7 + 3 = 4 + 3 = 7


(iv) 3(a + b) = 3(2 + 3) = 3(5) = 15 (v) 4a2


+ 2b = 4(2)2 + 2(3) = 4(4) + 2(3) = 16 + 6 = 22


Multiplication:


When numbers are multiplied, a new number is obtained. But when letters representing unknowns or variables are multiplied, we do not get a new letter. When two or more of the same letter are multiplied we simply square it or cube it and so on.


Example 4:


(i) a × a = a2 (ii)


c × c × c = c3


(iii) 3a × 2a = 6a2 (iv) 5 × a = 5a (v) a × b = ab


Adding & Subtraction: Letters representing unknowns or variables can be added and subtracted.


Let a = cost of one apple 3a = cost of three apples a + 3a = 4a = cost of four apples.


Example 5:


(i) a + 4a = 5a (ii) 2a + 3a + 3b = 5a + 3b (iii) 3a + 5a + 4a2 (iv) 4c2


+ 2a2 (v) a + b + a2


+ 3c + c = 4c2 + b2


+ 4c + 2a + 3b = 3a + 4b + a2 (vi) 5a + 3b –2a –6b = 3a –3b + b2


+ b = 8a + 6a2


+ b


81


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168