Question

Find the square of the following numbers without actual multiplication.

a) 86 b) 93 c) 71​

Answer 1

Answer:

please mark as brainiliest

Step-by-step explanation:

(a) (86)2=(80+6)2=(80)2+2×80×6+(6)2\left(86\right)^2=\left(80+6\right)^2=\left(80\right)^2+2\times80\times6+\left(6\right)^2(86)2=(80+6)2=(80)2+2×80×6+(6)2

[∵(a+b)2=a2+2ab+b2\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b)2=a2+2ab+b2

= 8100 + 540 + 9 = 8649

(b) (93)2=(90+3)2=(90)2+2×90×3+(3)2\left(93\right)^2=\left(90+3\right)^2=\left(90\right)^2+2\times90\times3+\left(3\right)^2(93)2=(90+3)2=(90)2+2×90×3+(3)2

[∵(a+b)2=a2+2ab+b2\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b)2=a2+2ab+b2]

= 8100 + 540 + 9 = 8649

(c) (71)2=(70+1)2=(70)2+2×70×1+(1)2\left(71\right)^2=\left(70+1\right)^2=\left(70\right)^2+2\times70\times1+\left(1\right)^2(71)2=(70+1)2=(70)2+2×70×1+(1)2

[∵(a+b)2=a2+2ab+b2\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b)2=a2+2ab+b2

= 4900 + 140 + 1 = 5041

Answer 2

Step-by-step explanation:

a) we can write as -

$(90 - 4) {}^{?}$

and on solving we get = 7396

similarly we can do all by -

$(90 + 3) {}^{2}$

and

$(70 + 1) {}^{2}$

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