# Using the formula

Question:

Using the formula (a + b)2 = (a2 + 2ab + b2), evaluate:

(i) (310)2

(ii) (508)2

(iii) (630)2

Solution:

(i) $310^{2}=(300+10)^{2}=\left(300^{2}+2(300 \times 10)+10^{2}\right)=90000+6000+100=96100$

(ii) $508^{2}=(500+8)^{2}=\left(500^{2}+2(500 \times 8)+8^{2}\right)=250000+8000+64=258064$

(iii) $630^{2}=(600+30)^{2}=\left(600^{2}+2(600 \times 30)+30^{2}\right)=360000+36000+900=396900$