the sum of two numbers is 7 and the sum of their cube is 133 find the sum of their squares
Answers
Answered by
7
let the two no . be x and y.
according to question:
x+y=7
and
let f(x)=x³+y³
f(x)=x³+(7-x)³
now differentiate with respect to x.
f'(x)=3x²-3(7-x)²
let f'(x)=0
3x²-3(7-x)²=0
3x²=3(7-x)²
x²=49+x²-14x
14x=49
2x=7
x=7/2
y=7/2
x²+y²=(7/2)²+(7/2)²=49/4+49/4=98/4=49/2=24.5
please mark me brainliest
according to question:
x+y=7
and
let f(x)=x³+y³
f(x)=x³+(7-x)³
now differentiate with respect to x.
f'(x)=3x²-3(7-x)²
let f'(x)=0
3x²-3(7-x)²=0
3x²=3(7-x)²
x²=49+x²-14x
14x=49
2x=7
x=7/2
y=7/2
x²+y²=(7/2)²+(7/2)²=49/4+49/4=98/4=49/2=24.5
please mark me brainliest
Similar questions