Answer
Verified
38.4k+ views
Hint- Here, we will be using elimination method to solve the given two equations in two variables.
Given equations are $a - b = 4{\text{ }} \to {\text{(1)}}$ and $a + b = 6{\text{ }} \to {\text{(2)}}$
The above two given equations have two variables $a$ and $b$.
Adding both the equations (1) and (2), we get
$a - b + a + b = 4 + 6 \Rightarrow 2a = 10 \Rightarrow a = 5$
Put the value of $a$ in equation (1), we get
$5 - b = 4 \Rightarrow b = 5 - 4 \Rightarrow b = 1$
So, the values of the two variables that satisfy the two given equations are $a = 5$ and $b = 1$.
Hence, $ab = 5 \times 1 = 5$
Therefore, the value of $ab$ is 5.
i.e., option A is correct.
Note- These types of problems of two equations in two variables can be solved easily using substitution method or elimination method. In the substitution method, we represent one variable in terms of another variable using one equation and substitute this value in the other equation in order to get the values of both variables.
Given equations are $a - b = 4{\text{ }} \to {\text{(1)}}$ and $a + b = 6{\text{ }} \to {\text{(2)}}$
The above two given equations have two variables $a$ and $b$.
Adding both the equations (1) and (2), we get
$a - b + a + b = 4 + 6 \Rightarrow 2a = 10 \Rightarrow a = 5$
Put the value of $a$ in equation (1), we get
$5 - b = 4 \Rightarrow b = 5 - 4 \Rightarrow b = 1$
So, the values of the two variables that satisfy the two given equations are $a = 5$ and $b = 1$.
Hence, $ab = 5 \times 1 = 5$
Therefore, the value of $ab$ is 5.
i.e., option A is correct.
Note- These types of problems of two equations in two variables can be solved easily using substitution method or elimination method. In the substitution method, we represent one variable in terms of another variable using one equation and substitute this value in the other equation in order to get the values of both variables.
Recently Updated Pages
Let gx 1 + x x and fx left beginarray20c 1x 0 0x 0 class 12 maths JEE_Main
The number of ways in which 5 boys and 3 girls can-class-12-maths-JEE_Main
Find dfracddxleft left sin x rightlog x right A left class 12 maths JEE_Main
Distance of the point x1y1z1from the line fracx x2l class 12 maths JEE_Main
In a box containing 100 eggs 10 eggs are rotten What class 12 maths JEE_Main
dfracddxex + 3log x A ex cdot x2x + 3 B ex cdot xx class 12 maths JEE_Main
Other Pages
The mole fraction of the solute in a 1 molal aqueous class 11 chemistry JEE_Main
Electric field due to uniformly charged sphere class 12 physics JEE_Main
Excluding stoppages the speed of a bus is 54 kmph and class 11 maths JEE_Main
Formula for number of images formed by two plane mirrors class 12 physics JEE_Main
The reaction of Zinc with dilute and concentrated nitric class 12 chemistry JEE_Main
Oxidation state of S in H2S2O8 is A 6 B 7 C +8 D 0 class 12 chemistry JEE_Main