Question

cross multiply x-3y-7=0 3x-3y-15=0​

Answer 1

Answer:

x = 4 and y = 1

Step-by-step explanation:

Given : x-3y-7=0 \\3x-3y-15=0

To Find : solve it by cross multiplication method

Solution:

Cross multiplication method

Equations : a_1x+b_1x+c_1=0\\a_2x+b_2x+c_2=0

\frac{x}{b_1c_2-c_1b_2}=\frac{y}{a_1c_2-a_2c_1} =\frac{1}{a_1b_2-a_2b_1}

Comparing the given equations

x-3y-7=0 \\3x-3y-15=0

\frac{x}{(-3)(-15)-(-7)(-3)}=\frac{y}{(1)(-15)-(3)(-7)} =\frac{1}{(1)(-3)-(3)(-3)}

\frac{x}{24}=\frac{y}{6} =\frac{1}{6}

\frac{x}{4}=\frac{y}{1} =\frac{1}{1}

So, x = 4 and y = 1

Answer 2

Step-by-step explanation:

x-3y-7=0 ................................ (i)

3x-3y-15=0 ............................. (ii)

x - 3y = 7.......................... (iii) [ From (i) ]

3x - 3y = 15. [ From (ii) ]

or, x - y = 5.......................... (iv)

now,

get by Subtraction (iii) and (iv)

x - 3y = 7

x - y = 5

- 2y = 2

=> y = (-1) .............................. (v)

now, x-y = 5

or, x - (-1) = 5

or, x+ 1 = 5

or, x = 4.

now,

The Diagnostic solution is —

x = 4

y = -1

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