limit as x approaches 4 (4-x) / (4- 2sqrt(x))
struggling with question need to find answer without using L'hospital rule I know the answer is 2 but i can't figure out how to get there... please help me
struggling with question need to find answer without using L'hospital rule I know the answer is 2 but i can't figure out how to get there... please help me
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Need to multiply by conjugate of denominator:
(4-x)(4+2√x) / (4 - 2√x)(4+2√x)
(4-x)(4+2√x) / (16 - 4x)
(4-x)(4+2√x) / (4)(4-x)
Cancel a 4-x
youre left with:
(4+2√x) / 4
Then you plug in 4:
4 + 2√4 / 4
4 + 4 / 4 = 2
Make sure to write limx-->4 on every part til you plug in limit, otherwise teach will deduct points.
(4-x)(4+2√x) / (4 - 2√x)(4+2√x)
(4-x)(4+2√x) / (16 - 4x)
(4-x)(4+2√x) / (4)(4-x)
Cancel a 4-x
youre left with:
(4+2√x) / 4
Then you plug in 4:
4 + 2√4 / 4
4 + 4 / 4 = 2
Make sure to write limx-->4 on every part til you plug in limit, otherwise teach will deduct points.
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Rationalize the denominator,
= lim(x→4)[(4-x)/(4-2√x)]
= lim(x→4)[(4-x)/2(2-√x)]
=lim(x→4)[(4-x)(2+√x)/2(2-√x)(2+√x)] Rationalize
=lim(x→4)[(4-x)(2+√x)/2(4-x)]
=lim(x→4)[((2+√x))/2]
=(2+√4)/2=(2+2)/2=4/2=2
I hope you understand
= lim(x→4)[(4-x)/(4-2√x)]
= lim(x→4)[(4-x)/2(2-√x)]
=lim(x→4)[(4-x)(2+√x)/2(2-√x)(2+√x)] Rationalize
=lim(x→4)[(4-x)(2+√x)/2(4-x)]
=lim(x→4)[((2+√x))/2]
=(2+√4)/2=(2+2)/2=4/2=2
I hope you understand