Question

please help me
class 10th
chapter 4
exercise 4.4
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Answer 1

Answer:

x+y=20

x-4*y-4=48

Step-by-step explanation:

use these equations

Answer 2

Let the present age of 1st friend = x

Given that :-

Sum of ages of friends is 20 years.

Present age of 1st friend + Present age of 2nd friend = 20

x + Present age of 2nd friend = 20

Present age of 2nd friend = 20 – x

Four years ago

Age of 1st friend = x – 4

Age of 2nd friend = (20 – x) – 4 = 16 – x

Product of their ages 4 years ago was 48.

(x – 4)(16 – x) = 48

x(16 – x) – 4(16 – x) = 48

16x – x² – 64 + 4x = 48

16x – x² – 64 + 4x = 48

– x² + 16x + 4x – 64 – 48 = 0

– x² + 20x – 112 = 0

x² – 20x + 112 = 0

Comparing the equation with ax² + bx + c

a = 1, b = – 20, c = 112

We know that,

D = b² – 4ac

D = ( – 20)² – (4 × 1 × 112)

D = ( – 20 × – 20 ) – (4 × 1 × 112)

D = 400 – 448

D = – 48

Since D > 0

The equation has no real roots.

Hence, the given situation is not possible.

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$\huge{Concept \: :-}$

• D < 0, no real roots.

• D = 0, two equal real roots.

• D > 0, two distinct real roots.

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