如何添加具有不同分母的 3 个分数?
分数可以定义为可以以A/B形式表示的数字,其中 A 和 B 是整数,B 不应等于零。在分数中,上部称为分子,下部称为分母。
示例: 1/2、4/5、-2/3 等。
分数的加法
要添加分数,有一条规则规定要添加的分数的分母应该相等。如果分数的分母不相等,则通过取分母的最低公倍数(LCM)使它们相等。
如何找到 LCM?
为了找到数字的 LCM(这里是分母),我们将使用除法方法。
让我们通过一个例子来理解这个方法,取两个数字 6 和 15 来使用除法找到 LCM。
第 1 步:制作一个包含左侧和右侧的表格,在右侧放置我们要查找的 LCM 的数字。
第 2 步:现在从最小的数字(不是 1)开始,并检查给定数字中是否有任何数字以此为倍数。在这个例子中,2 是 6 的因数,所以用它来除下一行中的 6。
第 3 步:现在在第二行 3 中,现在还剩下 15 个,只有 3 的因数是 3,所以取 3 来除它。 3 也是 15 的因数,所以也除以 15。结果是 1、5。
第 4 步:现在 5 是 5 的因数,所以除以 5,结果是 1, 1。
第 5 步:当我们得到所有数字的 1 时,该过程就完成了,现在将左侧的所有数字相乘,即 2、3、5,因此这些数字的倍数是 30。
不同分母的 3 个分数相加
添加不同分母的分数的步骤是:
第 1 步:找到分母的 LCM。
第 2 步:将 LCM 除以要添加的每个数字的分母。
第 3 步:将分子乘以商(在上述步骤中找到)。
第 4 步:将乘以商后得到的分子相加,例如简单的加法。
第 5 步:分母将是 LCM。
让我们取 3 个分母不同的分数,1/2、2/3、3/4
第 1 步:找到 2,3,4 的 LCM
第 2 步:将 LCM 除以要添加的每个数字的分母。
LCM = 12 所以除以每个数字(分母)
12/2 = 6 它是商 1
12/3 = 4 它是商 2
12/4 = 3 它是商 3
第 3 步:将分子乘以商(在上述步骤中找到)。
分子是 1、2、3,所以将它们与各自的商相乘。
1×6 = 6
2×4 = 8
3×3 = 9
第 4 步:将乘以商后得到的分子相加,例如简单的加法。
6 + 8 + 9 = 23 这是分子。
第 5 步:分母将是 LCM,所以它是 12。
答案是 23/12
交叉乘法
再次以上面的例子,所以添加 1/2, 2/3, 3/4
第 1 步:一次取两个分数,所以取 1/2 和 2/3
第2步:首先我们将找到分子项,因此我们将第一个数字的分子与第二个数字的分母相乘,同样我们将第二个数字的分子与第一个数字的分母相乘,并将两项相加得到分子。
1×3 + 2×2 = 7 这是分子
第3步:现在让我们找到分母,因为这将第一项的分母与第二项的分母相乘以获得分母项。
2×3 = 6,这是分母。
第 4 步:我们找到新项,即两个分数相加,在这种情况下,新分数是 7/6。
步骤 5:重复上述过程,取新分数 7/6 和第三分数 3/4。
最后,我们得到了与上面相同的答案。
示例问题
问题 1:将给定的分数相加,1/7、2/7、3/7。
回答:
In the given question the denominators are equal so simply add the numerators and the denominator will be 7.
Adding numerators 1+2+3 = 6
Denominator = 7
Answer = 6/7.
问题 2:求 7、3、12 的 LCM。
回答:
问题 3:将给定的分数相加,2/7、5/12、1/3。
回答:
Step 1: Finding LCM of 7,12,3
LCM we got is 84.
Step 2: Divide the LCM by the denominator of each number which are to be added.
LCM = 84 so divide it by each number (denominator)
84/7 = 12 it is quotient 1
84/12 = 7 it is quotient 2
84/4 = 21 it is quotient 3
Step 3: Multiply the numerator with the quotient ( found in the above step).
Numerator are 2, 5, 1 so multiply these with respective quotients.
2×12 = 24
5×7 = 35
1×21 = 21
Step 4: Add the numerators we get after multiplying with quotients like simple addition.
24 + 35 + 21 = 80 which is the numerator.
Step 5: Denominator will be the LCM so it is 84.
Answer is 80/84
问题 4:将给定的分数相加,4/5、3/10、1/3。
回答:
Step 1: Finding LCM of 5,10,3
LCM we got is 30.
Step 2: Divide the LCM by the denominator of each number which are to be added.
LCM = 30 so divide it by each number (denominator)
30/5 = 6 it is quotient 1
30/10 = 3 it is quotient 2
30/3 = 10 it is quotient 3
Step 3: Multiply the numerator with the quotient ( found in the above step).
Numerators are 4, 3, 1 so multiply these with respective quotients.
4×6 = 24
3×3 = 9
1×10 = 10
Step 4: Add the numerators we get after multiplying with quotients like simple addition.
24 + 9 + 10 = 43 which is the numerator.
Step 5: Denominator will be the LCM so it is 30.
Answer is 43/30
问题5:求7、3、12、13的LCM
回答:
问题 6:用叉乘法将给定的分数 1/3、1/4、1/2 相加。
回答:
Step 1: Take two fractions at a time so take 1/3 and 1/4
Step 2: First we will find the numerator terms so we multiply the numerator of the first number with the denominator of the second number and similarly we will multiply the numerator of the second number with the denominator of the first number and add both the terms to get the numerator.
1×4 + 1×3 = 7 which is numerator
Step 3: Now let’s find the denominator, for this multiply the denominator of the first term with the denominator of the second term to get the denominator term.
3×4 = 12 which is the denominator.
Step 4: We find the new term which is the addition of two fractions in this case new fraction is 7/12.
Step 5: Again taking 7/12 and third fraction which is 1/2.
Step 6: Finding numerator
7×2 + 1×12 = 26 which is numerator
Step 7: Finding denominator
12×2 = 24 which is the denominator
The answer is 26/24 now simplifying it we will get 13/12.
问题 7:用叉乘法将给定的分数 1/5、2/5、3/10 相加。
回答:
Step 1: Take two fractions at a time so take 1/5 and 2/5
Step 2: First we will find the numerator terms so we multiply the numerator of the first number with the denominator of the second number and similarly we will multiply the numerator of the second number with the denominator of the first number and add both the terms to get the numerator.
1×5 + 2×5 = 15 which is numerator
Step 3: Now let’s find the denominator, for this multiply the denominator of the first term with the denominator of the second term to get the denominator term.
5×5 = 25 which is the denominator.
Step 4: We find the new term which is the addition of two fractions in this case new fraction is 15/25 on dividing numerator and denominator by 5 we get 3/5.
Step 5: Now take 3/5 and the third fraction which is 3/10.
Step 6: Finding numerator
3×10 + 3×5 = 45 which is numerator
Step 7: Finding denominator
10×5 = 50 which is the denominator
The answer is 45/50 on dividing numerator and denominator by 5 we get 9/10.