ICSE Class X Math 2014 Solved Paper

Question : 42

Total: 52

Solve for x using the quadratic formula. Write your answer correct to two significant figures. (x−1)2−3x+4=0 .

Solution:

Given: ‌‌(x−1)2−3x+4=0
⇒x2+1−2x−3x+4‌=0
⇒‌x2−5x+5‌=0
Comparing with ax2+bx+c=0 , we get a= 1,b=−5,c=5 .
‌∴‌‌x=‌

−b±√b2−4ac

‌x=‌

−(−5)±√(−5)2−4(1)(5)

2×1

‌=‌

5±√25−20

=‌

5±√5

‌=‌

5±2.236

‌=‌

5+2.236

‌ and ‌‌

5−2.236

‌=‌

7.236

‌ and ‌‌

2.764

‌=3.618‌ and ‌1.382
‌=3.62‌ and ‌1.38

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