Find the modulus of the complex quantity $(2 - 3 i) (- 1 + 7 i)$ .

5 \sqrt{26}

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

\sqrt{26}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

5

No worries! We‘ve got your back. Try BYJU‘S free classes today!

10

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C $5 \sqrt{26}$
The given complex quantity is $(2 - 3 i) (- 1 + 7 i)$

Let $z_{1} = 2 - 3 i$ and $z_{2} = - 1 + 7 i$

Therefore, $| z_{1} | = \sqrt{2^{2} + (- 3)^{2}} = \sqrt{4 + 9} = \sqrt{13}$

And $| z_{2} | = \sqrt{(- 1)^{2} + 7^{2}} = \sqrt{1 + 49} = \sqrt{50} = 5 \sqrt{2}$

Therefore, the required modulus of the given complex quantity $= | z_{1} z_{2} | = | z_{1} | | z_{2} | = \sqrt{13} 5 \sqrt{2} = 5 \sqrt{26}$

Suggest Corrections